Much of Buddhism is presented and taught on the basis of RTC. Just look at the expositions in Jewel Ornament of Liberation, for instance.
If RTC is bunk, what do you do when teaching?
My sense is we need to move the emphasis to learning and away from teaching.
In other words, the primary task of the teacher is to create situations and environments in which people learn and build:
1. the possibilities and viability (addresses willingness) of venturing into the mystery
2. skills they need to do so
3. capacities they need to do so
What they do, then, is not up to the "teacher". The teacher has done his or her job.
What the teacher should not do is explain or try to convince the student that this is a good idea!