SCOTUS Case about Erroneous OPM Guidance

This was buried as a comment in a different thread, but I think it warrants top-line attention (credit to yasssssplease):

There’s actually a 1990 SCOTUS case that says that even if you get erroneous information from OPM, you’re not entitled to any benefits if not allowed by statute.

From https://www.oyez.org/cases/1989/88-1943 :

Question: Does receipt of erroneous information from a government employee entitle a claimant to benefits he would not otherwise receive?
Conclusion: No.

On one hand, I don't want to give the clown-crew any credit for even knowing about this SCOTUS case. On the other hand, this could be the entire basis for screwing over anyone who takes the fork offer. This could be the whole ball of wax right here.