I wouldn't be willing to spend money on one if it didn't, and I'd have to remove the headset every time someone wanted my attention if I can't find the keyboard. Not to mention, the virtual keyboard DOES work in single player for some reason.
This happens on my Galaxy S7 with Android Marshmallow when trying to connect to online servers with Gear VR on 0.15.4 while using a Steel Series Stratus XL. The chat window will work on single player maps, but it will not pop up in multiplayer games. Mega_Spud's options menu is non existent in the Gear VR- when under keyboards, there's some kind of options for QWERTY and variations of that, but no apparent way to change input methods.
It's not only the realms server where the bug can be replicated- even connecting via IP can produce the same result.