Just for S&G I just played the beginning of my bluray of BR2049 in both Dolby and DTS since the disc has both. and there's reasonable bass content...no difference at that level (7.1). Don't really have things setup to accommodate a downmix in the player, no specific 2ch output options that I see.....perhaps if I had it hooked it up with 2ch analog to force it, but I don't.
I also just listened to the same bit in 2ch having my avr downmix to 2.0 (by turning other speakers/subs off) and neither sounds bass attenuated, and that's both with using the Dolby TrueHD/DTS MAHD and "stereo" settings (with subs turned off still). Can't say bass shy came into my thoughts at all....