Flopped? He didn't flop, he just totally failed in his slide. His body whipped around and he smacked his head hard on the turf.
The Giants did call a timeout, but then it was ruled "an official's timeout" and Giants got it back.
I'll have to peruse when an official's timeout can be used. Although in this case I suspect it may be due to someone determining that Cutlets had to come out for concussion eval.