He's all about acceleration off the line. If he flubs his standing start and doesn't muscle out a huge lead then it's over. He practices specifically for maximum output, not stamina, and he's probably got a low spinning gearing for more power, hence the standing starts. Once he's behind there's no way he can spin up his ham hocks and close the lead.
I'm hoping the lady cyclists figured this out and know to just tire him out off the line and ignore him after.
Absolutely...He will have very little stamina these days. Strong as an ox, yes, but his stamina is going to be severly compromised due to his general unfittness and his breathing will be very far from efficient.
I can imagine he is stubborn, and very determined to show those pesky women who is boss, but i imagine his performance starts flagging the more heats he has to do. In his current state he would probably pass out, or dns, if he went into a competition that had maximum entries so loads of heats and potential re-matches in each heat if it is 'best of 3' format.
A little bit of info for any newbies.....
The only event he does with a standing start, where the timing immediately starts, is his time trial event. I think it is 500m for women and 1km for men. It is just one rider against the clock and no other rider influences the result.
His other races are the 200m sprint and the Keirin. The former is 2-3 riders, in each heat(can be eliminator or best of 3 formats) who gently roll off and kinda tease each ither for a couple of laps and then the sprint starts with the last 200m timed.
The keirin, on the other hand, has several riders, in each heat, depending on how many entries there are, and they start off gently and tag in behind an ebike/moped/derny for a couple of laps before the sprint really gets going. It depends on how many riders you have but you will get a few top finishers going straight through to the next heat while the lower finishers have to race lower finishers from other heats to go further into the competition. Sometimes it is run where below a certain position will mean the end of your competition.
Keirin has been tamed down as whatever the machine is that leads them round goes much slower, these days. It used to gradually increase speed from 20ish mph and by the time the sprint really started they were elbow to elbow at about 50mph.
.....and back to your point
Due to his poor physical condition i would say he definitely struggles big time with the Keirin, as it is over several laps, so chances are high he will get beaten in that. In the sprint races i would suggest to the women, he is up against, that they should just start off as fast as they dare as Rhys will run out of puff, literally, way before they do and even when they start flagging, in the last lap, he will be too far behind to catch up, or if he has managed to slipstream will probably be gasping for air and fold in that last lap. They just need to do whatever hus chub wont allow him to do. He is literally wearing a target.