Nice trick, thanks!
Seems more like a bug than an intentional feature.
I’ve been thinking for a while that it would nice to have previous / next arrows next to the sample name in Halion and Sampler track so you could switch out samples on the fly while the sequencer is running.
I mean, this is something i could do with my Akai S950 back in 1990!
Here’s another useful workaround for auditioning samples in the Media bay (scroll down to my first post):