There's no scenario in which this reference would be anything better than "He/she worked here from date A to date B."

The backchannel reference check is already blown, make no mistake.

It's a firing. You're now, instead of being entitled to benefits (in most areas) or being able to negotiate for them, being given absolutely nothing.

Also, a mutual non-disparagement agreement and severance is extremely easy to negotiate for.

And then guess what? Instead of being fucked in that backchannel reference check, _everyone_ takes pause due to the potential consequences.

Sure, a backchannel reference check might still happen, but if and when you find out about it: good night.