I understand your reasons, a part of me agrees with you (the advanced glitches of Riders are the most difficult among the Sonic racing games by far), but this leaves me with many doubts.
1) In Dolphin is there a sure way to know if manipulation is used? Show fps help on something?
2) This is for all competition. If Dolphin is banned, why not ban all GCN emulators? Because by the current rules, I could use another one (if it is stable).
3) In the case that the GCN emulators are banned, in the current rules I could use a PS2 or Xbox emulators for Riders. Why would these be allowed (if they were stable, I've never tried them) and not Dolphin (more stable emulator for Riders)? This question may also be valid for other games. I would recommend thinking well the emulators that will allow. You could make an official list of emulators allowed per game, for example.
4) Because nobody has noticed inaccuracies in Riders (because the game runs stable on decent PCs), why not create special rules for Riders? To prevent TAS problems, emulators are not allowed for top5 or top10 times, or something like that. The idea is that, at least, normal players (not necessarily top) can use it.
5) Recently, there are players who submitted Dolphin stats, but the category (Babylon Guardian Single Lap) is one of the best to get a good position without too much effort due to optimizations in recent years. Babylon Guardian is the simplest track in this game. What would happen to them? I request to maintain those times (in total, 3 Babylon Guardian Single Lap Races), if possible.
If TSC keeps the idea of banning Dolphin for all games without special rules for Riders, okay, I'll accept it. It does not complicate me, but you will take away the possibility for new players to participate. But I must say that there are solutions to their fears (which are understandable and I would also have them in the case of happening), such as allowing submit times non-top5 or non-top10, things that would help our community. In Riders you can play in 3 ways: Glitched (only 3 players are capable), 350 Speed (High Booster) and 250 Speed. At least, 250 Speed (and some 350 Speed) times could be submitted without problems, in the case of a non-top10. Special rules like this one is much better than nothing.