It's a valiant effort, but I think it's pretty clear who it is: Bob Reynolds a.k.a. Sentry (played by Lewis Pullman). Those who have been paying attention to Thunderbolts* will recall that Bob was prominently featured as a character in the first trailer for the blockbuster that arrived in September,

Throughout the trailer, we see a dark caped figure flying in the sky, zapping people and leaving behind shadowy dust. That is the Void, arch-enemy to the Sentry a.k.a. Bob. Also, the Void is the Sentry a.k.a. Bob. They’re the same person.