I wouldn't flip out if Cam was back, but it doesn't inspire much confidence in me. His leadership was great, no doubt. If the weapons improved drastically and commanded respect (and he is 3/4 of a year removed from COVID), I can see the case for improvement from him - even if he can't throw particularly well, he can hit guys sometimes, which opens more space for him to run and otherwise improvise. They wouldn't be Super Bowl contenders but they might be a playoff team in that scenario.
That said - it feels like a band-aid. He's probably not going to sign more than a 1-year deal, so you'd need to have some kind of succession plan in place. Being a bridge until 2022 when Mac Jones or someone else takes over, sure. Would Cam want to do that, though? And will Bill want to go through such a band-aid season or will he want to contend right away?