Nice encounter.
I’ve found 99% of MTBers to be at least friendly and supportive. Often, as you found, they’re beyond friendly, with an almost worship-like attitude about the hardcore-ness of a unicyclist riding the same trails they’re riding.
I think non-uni riders think it’s close to impossible just to ride a unicycle, and when they see us riding technical terrain, they’re just blown away.
Now I’m off to a MTB race, to get a little more ego-stroking from them MTBers!