So?
I feel like you're retreating into a cloud of "who can possibly know, eh?"
It seems like a very counterintuitive claim that a series of warp storms that formed because Slaanesh was about to be born soon, within the next few millennia, would hang around for very long if Slaanesh wasn't about to be born anymore. Sure, anything's possible, but some things are a lot more plausible than others.
Evidently your not up to speed on this topic. So welcome to talking about the Warp, where any notion of time is a shot in the infinite dark.
If your thinking it's counterintuitive then you are clearly confused by something. I'll explain the difference between the canon version and this potential versions to help you.
First how it happened in canon where Slannesh is born.
First cause, is Slaanesh's gestation begins. Which has the side effect of warp storms popping up across the galaxy making travel impossible.
Roughly 5 millennia go by and the second cause takes place, her birth. The effect is a massive psychic explosion that creates the eye and blows away all the warp storms.
Now if she's not born.
First cause, is Slaanesh's gestation begins. Which has the side effect of warp storms popping up across the galaxy making travel impossible.
Roughly 5 millennia go by and the second cause takes place, she isn't born. The effect, she's not creating additional warp storms as a side effect anymore, among numerous other potential effects.
But if none of those effects are a massive psychic explosion, or at least similar in function to cause the current lingering warp storms to disperse. Then all you can do is wait, since they aren't gonna do it till they run out of steam.
And that has to do with time and the warp, which again "any, notion, of, time, is, a, shot, in, the, infinite, dark" when the warp is concerned.
Aye, I'll confirm that neither option affects your eventual tech tree development, and it's only if you mess up real hard after declining that next arc will be … not harder, but you'll end up in different circumstances. If you want a guaranteed safe start to your interstellar days and room to expand without the Dominion noticing you for the duration of the grace period (which will be a notable mechanic a la the psyker blooms from mouli's Keeping To The Dream quest), then I'd pick Accept.
That seems really illogical, since if the Deny option requires resources and what not to be used on aspects like getting rid of the curse in the stone and moving toward effecting the Fall. Then those are resources that aren't focused on improvement and research.
And in contrast the Accept option would guarantee all resources go into improvement and research. So how could it possibly not effect tech tree development and development in an of itself.