That's a really interesting bypass; I wonder how this can be patched or mitigated considering the module is entirely loaded from memory. Short of setting noexec on temporary directories, I can't think of any quick short term fixes.
Edit: Re-read the blog post and looked at the Github repo for the code- looks like this is more of a proof of concept of a SELinux confine bypass, as the kernel needs to be compiled with CONFIG_SECURITY_SELINUX_DEVELOP set. See the readme here, there's some more notes that weren't included in the blog post.
Bitwarden is probably a lot safer if you self host (which I do). You do inherently lose some security by having a server that holds your encrypted password database, but my instance isn't exposed to the internet.