You’re somewhat overestimating the security risk in this case. As stated in the conflux specifications ( 329-traffic-splitting - Tor design proposals ), conflux is currently only used for non-Onion services. Conflux support for Onion hidden services is under development in arti and partially in tor. However, for those running Onion services and not using Tor for the regular network, conflux shouldn’t affect or interfere with vanguards at all.
The problem is not about lack of conflux in Onion Services traffic. It is about lack of complete vanguards support due to incompatibility with conflux feature. Full mode is essential for anonymity of “high uptime” Onion Services, which most of publicly accessible onions are. Tor Project admits it in article you previously linked:
Full, for onion services with high uptimes (longer than one month)
There also seem to be differences between the Tor Project and Mike Perry’s approach. The implementation of the bandguards subsystem was not mentioned. I assume that “Relaxed path building restrictions” refer as the equivalent of the Rendguard subsystem:
Arti 1.0.0: Ready for production use
It seems that their blog article and official documentation are contradictory on this:
Arti is not yet ready for production use, but it is ready for testing and experimentation.