Can public political criticism of my alma mater result in my BA being revoked 35 years later? Perhaps it is a sign of paranoia that I even ask, but is there a chance that the private college I got my BA from back in the 1980s would revoke my degree if I were to publicly complain about its political stances?
Unfortunately, I have never donated significantly to the college, so my views don't hold any real force.
I doubt they would do so. And if they did, I find it unlikely that it would set off a chain reaction. But theoretically, my teaching degree depends in part on my MA, which in turn depends in part on my BA. Theoretically, if my BA got revoked, I could lose my teaching accreditation and hence my job. But can they?

Thank you to everyone for these thoughtful and detailed responses. My fears have been broadly dispelled, although some anxienty remains. I probably have more to fear in my current setting directly, than through a chain reaction involving my degree.
I have posted some thoughts in the comments under the first response and will remain engaged in the discussions above.
I've been working in Academia for the past ten years. The only cases of degree revocation that I am aware of were due to severe cases of academic misconduct such as plagiarism, fraud, or large-scale cheating. The rationale is that gross academic misconduct invalidates the achievement the degree should certify.
Revocations on grounds of expression of (political) disagreement with the issuing institution are unheard of in rule-of-law democracies. I've never heard of such a case, although it would certainly have become very well-known.