This is the same "private" company which has been ignoring over 2000+ people's votes for Monero support. It's ironic how they are now making a cryptocurrency wallet for bitcoin.
The reason they don't support Monero was adressed in a recent podcast "OptOut" with the CEO of Proton.
TLDR; they fear the biggest companies for auditing their finances, won't work with them if they do. Which is reasonable, they are a business after all.