Your OP was clickbaity and sensationalized.
It's ok to want Mullvad to move away from gmail for ideological reasons but that was not your tone.
You claimed that because of that "they don't give a shit about user privacy". You thus implied it affected user privacy when that's clearly not true.
Yes a user can doxx all his PII in a customer support email and then reuse the same mullvad account, but at that point, that's more of an L to him than to mullvad. Personal responsibility is irreplaceable. 

 Yes you’re correct that the burden of responsibility falls on the individual for anything in life.  But Mullvad is misrepresenting themselves here.  If they really cared, they wouldn’t do this.  My tone is to purposefully create negative consequences for the use of Big Tech, to force them to change.  As if I worded it in a “wouldn’t it be nice” way, then I would be ignored.