Route F spoiler but I guess if you haven't play that part this won't give you much clue.
Though it may sound kind of aggressive, isn't this some chance (you could say only chance) we possibly kill Mephis by using the c4 given the lethality of those bombs is enough. You could put them somewhere near the door(most likely the front door), or even with the bodies of Jack and Dominic which will probably attract Mephis' attention if able to make him come closer.
The detonation could be a problem though. If the ECM jammer is still working, guess the detonator won't work well. Benson could shoot the bomb though, much easier than shooting Mephis. But, yeah, we know what happened in day 22 which was also suspicious.
It seems off as something that Dave would decide on. But in "some" storyline, Dave could actually get driven by the thoughts of revenge (for all these danger and death of him, his friends and most importantly, his dad), let alone there already exists such example when Dave did "kill" someone in revenge. So such story development seems resonable, to me at least.
Even at the very least, I think throwing the bombs away is much safer than trying to disarm them. But now that Thanatos can ensure the security this won't be much a problem.
Still, just some if-storylines which I would definitely try. Or maybe I just want to see more "dark sides" of Dave. There are many mysteries that I want to find answers, looking forward to what could happen in the future. Thanks for your work, Grizz!