Ruben went down theatrically for sure, but that doesn't make it not a foul, he was pushed in the back and probably tripped too by the second player coming in, Rowe is clutching at straws and blaming the whole defeat on that as if it was nothing to do with him.
They had two players injured at the same time and he chose to keep his injured goalkeeper on and have 11 players than play with 10, thats completely on him, not sure if that was his 3rd sub or he just made other subs later (if he did then more fool him).
I wonder if he'd made 3 subs, then a player went off injured, would he have been able to bring on a sub in extra time when you're allowed a 4th to get back up to 11 players? Presumably he could have hobbled back on to the pitch at the start of extra time to be subbed in this scenario?
Anyway, the crux of it is, Rowe done goofed, two of his players very clearly dived, Notts could've/should've had two penalties so he shouldn't be blaming the ref but you can see why he'd say something worthy of a 4 game ban, he's a terrible loser.