So, Apple breaks all multipoint devices unless all connection are from Apple devices? Weird.
It would breaks if it is the first to connect, usually it is. it messes also with smart tv.
Regarding phone call, I can’t tell as my iphone is my phone actually :) But i don’t think it would happen with Android, we would have heard about it, even though it uses same bluetooth stack than Linux.
Though, I would like to thank @Oisteink , indeed, if you disable bluetooth from the Settings (not the drop down panel), it will remain disabled, stupid UX.
note: that I tested with sony and sennheiser bt headsets too.