I guess the takeaway from the xz backdoor situation is:

If you’re an open-source project maintainer, and somebody starts getting on your case for not doing enough free work for them, you reply “big Jia Tan energy there” and then block them forever.

@zarfeblong My policy has always been to express my regrets that it's not working out and "on behalf of management" to offer them a refund of twice what they paid, upon submission of a receipt.

Some laugh and get it, the rest go away. Bye, the rest.