I somewhat agree with everything you said, up until the last statement about straps. You shouldn't be using straps on Olympic lifts, that's what a "hook" grip is for. Although, tough to do continuous reps with a hook grip without resetting, so I can see why he would use straps. Straps have nothing to do with safety in the weight room, its more for when your grip is the limiting strength factor. That being said, it's still impressive.
And a couple quick things about 400 lb bench press in football.
1. These guys are football players, not powerlifters. They are probably not testing their 1 RM very often, to decrease the chance for injuries. They should be working more explosive power with bands and chains.
2. Is a 400 lb bench press impressive? When comparing it to a 120+kg powerlifter, no it's not. When comparing it to the average D-1 OL, yes.
3. Why is it impressive? Because I'm sure those guys are benching with a close grip, or at least a lot more narrow grip than a wide powerlifting grip. Close grip benching with elbows tucked is more specific for blocking, but it's also a lot harder to do. Not to mention the arm length of those OL, those are some long levers and they are moving the weight almost a couple feet. If all of these guys trained specifically for powerlifting, widened their grip to the knurled rings, arched their back, flared their elbows out, and primarily did sets of 1-2 reps, I bet they could put up 500+ lbs with only having to move the bar about 12". But of course, that wouldn't do much for football blocking.
TL;DR
These are football players training for specific football movements, not powerlifters. If they wanted to be stronger on a 1 RM, they could be, but that's not the point of football. Football is about explosive power throughout an entire game, not about how much they can lift 1 single time.