My take is that you can't have a serious e-sport cycling scene with the current tech. This guy was caught because he was greedy and the cheat was too obvious. What about all the others that could be doing the same but in a smarter way. There is no way as an honest cyclist to know you were beaten fairly. (Maybe you can be sure you were not).

The protocols (ANT+ in particular) are totally insecure and it's totally possible to MITM them. The obvious solution would be to upgrade those and start sending data over an encrypted channel instead. Still, this is only going to help momentarily and discourage the hobbyist cheaters. People are starting on PC games using very sophisticated setup with dedicated PCI hardware connected to a second computer where the cheat software actually run.

If the devices get secure, people will start cheating at the software level. If the stake are high enough (and there are for those people hoping to get into a World Championship), they will do anything to get an edge.

I think it's hopeless to hope to make those online race as anything serious. It can be a fun hobby and way to exercice but any serious competition will need to take place in person. For cycling, it probably means the old fashion way: on the road.