This is tough. You really need more RBs. Since you already have Gronk, Ridley appears to help your team much more than Hernandez. And I'm not sure trade value you'd get for Hernandez with him not having played for a while. How many teams is this? If it's 10, I'd feel good about dropping Hernandez and hope for the best. Alternatively, you can play chicken and hope Ridley lasts past this weekend - then drop the Giants DEF for him. The fact that he hasn't been picked up yet suggests there's a reasonable shot he lasts a little longer.
If it were me ... again, tough call ... but I wouldn't chance it and drop Hernandez now (regardless of number of teams in league). Then I'd hope I can reclaim him after the weekend (dropping Giants). I doubt Hernandez will put up good numbers (he probably won't even play). With other teams facing bye week issues, he's not super attractive at the moment. Does your flex allow for TEs, or is it a traditional R/W flex? If you can't play a TE there, Gronk + Hernandez doesn't make much sense unless you can trade one (and sorry to say, you should've done that a couple of weeks ago when they're combined value was highest). They can't cover the other's bye week.
Hope that helped! Please look at mine in return: viewtopic.php?t=502187