On the SWAPA litig & OldnGrounded:
That's the conventional wisdom plus, in this instance, it's more than just conventionally correct.
But even in the - in comparative terms - small-stakes cases I've litigated, games of chicken did get played. While not predicting this (and for the same reasons you stated), still I could see a desperate litigant anticipating advantage from a tarnished witness taking the Fifth.
Actually, one also wonders what terms were stated, meaning in writing, upon this person's leaving the employment service of Boeing?