No, I'm really not. I'm aware that we're not out-and-out inviting them into our power bloc, if it can even be called that. But the fact of the matter is that that is how the rest of the Empire, especially the parts of the Empire hostile to us, are going to perceive it and react to it, and likely how they'll address it if they decide to confront us about it during the next Elector's Meet. I agree that we will be making diplomatic overtures with them inevitably, but can't help but disagree on what we can consider as "armour".
Sure, we'll be openly meeting them eventually. But by openly meeting them now, without seeking any sort of approval or advice from the main authority of the Empire itself before making open diplomatic alliances with a foreign power, then we're quite literally giving them a weapon to attack us with, when the next Elector's Meet rolls around. They can easily call this out as any number of things. Colluding with a foreign power, possibly acting against the Empire's best interest, etc. etc. Magnus is great, he likes us, and he's very reasonable. I think if we approached him with this diplomatic opportunity in an official capacity, he'd welcome it with open arms. But he's still the Emperor. If a bunch of Elector Counts accuse one of their number of colluding with a foreign power without the consent or knowledge of the rest of the Empire, in a manner that might destabilize the Emperor and the rest of the Elector Counts' authority, even if he trusts us, and knows that we wouldn't do anything to harm the Empire, he'd still have to treat the accusation seriously in his capacity as the Emperor. I think we'd probably win the ensuing political confrontation. But at the end of the day, whoever wins the confrontation, the Empire loses.
Bluntly speaking, I think we'd be better kicking the can down the road for a couple of years, getting official approval from Magnus to engage them in open diplomatic talks and meetings, and leaving those who will be burned by the alliance we're forging here with no real avenue of attack against it, even if it introduces a minimal risk of us, Stephan or Ortrud dying in the, what, five years it'd take to get this officially approved, tops? It's a risk, sure, but a rather slight one, I can't help but feel, and one that's significantly outweighed by the repercussions of rushing things just because "we might die".
Edit: And yes, I'm sure someone could make the argument about how we've done the same thing with Kislev and the Dwarfs and the High Elves or what have you, and they'd have something of a point. But that's that, and this is this. Kislev is a human state that the Empire's had plenty of dealings with in the past, the Dwarfs have been friends of mankind since the dawn of the Empire, and a High Elf founded the Colleges of Magic, and is a friend of the Emperor. Laurelorn, and the Wood Elves at large, are a group that the Empire as a whole has had very little in the way of dealings with, and many of those dealings have been decidedly hostile.