I'm sure that's true.

But then it's not my problem.

FastMail made an agreement - $15 in exchange for a lifetime member account.

Now they don't want to honour that agreement.

And they've created work for me: What to do about my father's email account?

I have his email address as part of the domain that I have associated with my (legacy) FastMail enhanced account. They've discontinued family accounts for new signups.