Even if our various bakemono creation charms don't (and I think they can, but don't happen to have those rules handy at work), Companions of the Hunter explicitly does. Buying it for Lydia would also be useful in general and would maybe involve us not shortchanging her on xp for once (since it would be spending xp on a goal that's explicitly Molly's, not Lydia's)
We can't and shouldn't expect Lydia to tie one of her very few slots for the companions of the hunter (up to Essence level of animals) to protect our godson. That's for us to do, not her.
1) Spirits cant cross thresholds without being invited in by a resident with the authority to extend that invitation, they can be banished, and they are vulnerable to various vectors that embodied minions are not.
They have their place; bodyguarding a normal mortal child in a variety of situations is not one of them.
Not how emanations work. They are bound to their keystones, and normally exist in a spirit world. They manifest paying Willpower (which is why it's willpower 10 build). Bodyguarding a mortal child (I will only agree with "normal" when I see the child and confirm no magical gift, and only reluctantly even then, given who their godmother is) is exactly what a spirit could do.
If guardian deity of an Order of Cauldron is a viable possiblity, and it is by WoG, then guardian deity for a single child is too. More so, even.
2) Street-level hostiles can be deterred by a mundane medium-size dog from the local pound with a loud bark and sharp teeth, let alone something from one of the serious guard dog breeds like a German/Eastern Shepherd or a Malinois.
If the issue was just street-level minions, I'd vote to get him a normal Great Pyrenees and be done with it.
We have different understanding of what a street level is. Check the build again. A spirit that has 12 dice for combat, flight, soaks agg (and has soak 7), and does all defensive combat as -3 DC (because of the merits), while resisting all mind altering magic with +3 DC for the enemy, should be able to handle teams of gunmen and most likely a vampire elder. Dogs can't, and, much more importantly - you can't take dogs to school or to many other places. The designed guardian, on the other hand, can stay with their charge at all times. Medicine dots should allow for first aid too. Perception + awareness/alertness cranked up to literal 11 gives it superhuman senses to detect threats both mundane and supernatural. Athletics 5 + Strength 7 allows it to open doors, clear off rubble, etc to rescue its charge from any cave-in or building collapse or some such. Human hands can do fine manipulation (dexterity 7). Telepathy allows it to call for help and to communicate with its charge. Flight gives it options to flee, again with its charge.
Dogs, even spirit-enchanted dogs, can't compare in utility. They can't be taken to many places. They can't do fine manipulation (so no first aid, or opening doors, or operating an ATM while on the run). They are always manifested. They can't fly or drag their charge away easily.
3) Immaterial spirits dont appear to roll around with Strength and Dexterity ratings anyway.
Certainly nothing that high.
And that doesnt support an ability to get away while carrying a child anyway.
Normal ones don't. This is a 5 dot custom-designed god. That's a major working. Like, city god of Chicago major (even if such a city god is likely to go into custom build area, with 5 dot build being a nucleus). Everything I wrote is system-legal, and not even cheese, I think.
4) We use normal animal-smart dogs to guard children and livestock IRL.
Livestock guardian animals literally live with their flocks with weeks at a time and keep them safe in the absence of the farmer.
We have service animals, that, and I'm quoting the Wikipedia article here:
Animal-smart dogs can be very, very smart at the high end.
Furthermore, intelligence-augmentation is supported in the fomor-building process.
We also use nannies, and other human servants, and if you have an option to choose between human and an animal, you'll almost always will choose human.
Point is - the designed spirit should be able to provide far greater protection and utility (because it has human hands and great dexterity) right out of chargen, and it time, as they accumulate XP and learn, even more so. While being more stealthy than a dog.
Cant just train one and plop it into just any new tech; a spirit that awoke in an apartment building isnt necessarily going to translate to a warehouse. Molly being able to HMP shit is an Exalted miracle, not the norm.
Not how I wrote it, at least, to chime in. While the spirits certainly have a degree of preference, if their housing is destroyed, they'll reincarnate, either in another device, or directly into nooshpere, from where they can choose what to inhabit (choose being a misnomer for below-sapience spirits). At least this is how I wrote this.