Does your theory about Tim and timing (lol) involved somehow the fact most of us can recognize how season 3-4-5 had the best set up and time for a slow burn (if we streeeeech we can go to season six but I always though the whole sperm and lighting arc would have been juicier with a stabling relationship but Iโm derailing)
Partly, yes! I've always said I really do believe that Tim wants to make buddie happen, but lately it seems that he keeps getting in his own way.
Now personally I don't think Eddie was written as ambiguously queer from the beginning, though I definitely think there are compelling arguments for that being true as well. But buddie in S2 is written very differently than buddie in any other season. Partly it's because they still were establishing the characters, but from S3 onward they treat their relationship with a gravitas that wasn't there in S2. The christmas elf and the ig live comments were nods to the fandom and its buddie shippers, that's something Tim himself has confirmed. But they never did anything similar again after that. S3 kicks off with Buck (BFF) and "there's nobody in this world I trust with my son more than you," and from then on they've pretty much been each other's most significant other.
As you say, and as we know from Oliver's comments post 7x04, it seems like S4 and S5 were going to be the original catalysts for bi Buck and queer Eddie, but Fox being Fox meant they had to pivot. And that leads me into the theory I have about Tim and buddie: I think Tim has a very specific idea of how he wants them to get together, one that requires some setup from the show's narrative to put them in the places where he wants them. But things keep getting in his way (Fox saying no, writers strike, him changing his mind on how long he wants to drag out the bucktommy plot during 7B, ABC forcing them to shuffle some episodes around, Peter unexpectedly leaving the show) and instead of adapting he restarts the plot every time. Which is why the development of buddie is now stuck again, because the show has to deal with one of its key characters being gone, and ABC demanded the space arc be extended to four episodes, and... and it never ends! But he still seems to be trying to loop around yet another rotation, thinking maybe he can finally change tracks to the ones he's been trying to reach on the next lap.
And it's exhausting. At this point it really is. They've let the cat further out of the bag than ever before with Buck being openly bi and Tommy breaking up with him because of Eddie, but for some reason they're still trying to pretend nobody saw the cat and that we'll all agree to just think boy, that bag sure seems to be moving at times, wonder if something is inside it? Constantly putting Ravi in with buddie this season feels part of this too. But yeah, I think Tim has a plan he isn't willing to deviate from, and that's now dragging not just buddie but the rest of the show down with it as well.