You need to make it a big public stink in that case. Make it really public and have lots of people join in.Or they’ll say “wait a minute, we did something wrong here, we’re losing thousands of donors, let’s right that wrong.”
And then all that happens is that one hospital that's doing it just folds the policy into "medical survival risk" instead of a separate line and goes on as before.
The "we will threaten to make sure more people die unless you do what we want" approach didn't really work for MwM blood donation ban because most people who care about the issue aren't sociopaths, and I suspect it won't work here.