Yes, but it's hardly surprising that criminal investigations tend to evaporate some privacy standards very quickly. ProtonMail doesn't want to get hit by the stick too.
And before anyone suggests that PM should have been more "open/honest" about this, I disagree, the fact that a criminal investigation will do this is well known and mentioning it would be akin to asking your bank to plaster "if the world economy implodes, we might not be able to pay out your account" all over their frontpages.
