I dunno, I ride and I wouldn't follow that closely. It isn't just about how quickly you can stop - an average motorcycle has awesome stopping power - it's also about how quickly the guy behind you can stop. You have no control over how closely the car behind you can stop, and if he's too close, then the quickest you can stop is however quickly he can stop. Unless you wish to be his hood ornament. I've had panic stop situations where I've actually lifted my legs for impact because I didn't think the guy behind me could stop, and once the girl behind me couldn't stop but lost control, went around me, and smacked into the truck stopped in front of me before hitting the concrete bridge rail. In a panic situation, distance is your best friend.
That said, I completely agree with your analysis on what he should have done. Foreign objects in the road are a constant hazard, and any rider needs to be prepared and vigilant.
I absolutely hate assholes who don't give riders enough space.
It shouldn't matter how fast a bike has to stop or what happened in front of them, I give more distance to bikes than to other drivers. Why? A car will absorb energy in the event all the wrong things happen - I'm not trying to have a flattened rider on my conscience.
I speed, I enjoy driving, and sometimes I get very annoyed with people going slow in the left lane and not moving over, but I rarely have a rider annoy me so they get a ton of space.
Except for this one group of slow old assholes - two Harleys, one in each lane of a two-lane highway (well, two Southbound lanes). Both going at the same pace, which was a pace slower than most traffic ahead of them and behind them.
I used all kinds of signalling methods, lights, hands, etc, to get this guy to be less ignorant and share the damn road. He ended up giving me a "back off" because I was definitely in his comfort zone, which I did back off, but I continued to make my point. Eventually he finally got the idea and got in the other lane. I gave a wide berth and continued on my way.
Don't be like those idiots, that's all I ask. And that goes for being in or on any vehicle.