So because the readers wont consider other options, then it's the writers fault? thats certainly going to dissapoint anyone with a plot-twist in mind.
Bold: Ok, did you just completely ignore that the cop's speech box in that very panel actually says 'Thunder and lightning' when it shows us the thunderbolt and the old clubhouse? How the hell was that supposed to tease Wally when it so bluntly tells us who it is?And there are plenty of ways to tease a character and not make it seem they're alluding to Wally. Like for instance not ending on a lighting bolt. Teasing in ways that could easily seem like they are alluding to the return of the big omission from this group only sets them up to disappoint their readers. Does that handcuff them a bit, sure, but it is what it is. Its something they have to be aware of given the generation of characters they are using here.
It's not like the Flash has a patent on using lightning after all.