there are actually a couple "fairly obvious loopholes" scattered throughout the NESBA handbook, so I see where the question comes from.
I think what he's saying (and i don't disagree) is that the site shouldn't allow you to register for a date when your membership will be expired - at least not without warning. I didn't encounter this scenario with my membership, so I can't speak to how it currently works.
there are going to be people who prefer it both ways; those who know their membership expires in June, and don't want to pay the renewal right now just to book a date in July, and those who will cry foul when they book a July date and are told they owe $75 when they show up at the track.
The simple solution is a disclaimer - if my membership expires next week, and I book a bunch of events today, I get a pop up notifying me "your membership is currently valid, but will expire prior to X number of events you have booked - either remove these X dates from your shopping cart by clicking _____, or click _____ to acknowledge that you understand you must renew your membership prior to attending these events; and proceed to checkout."