If the answer fixes a problem, great.
It's not that we hate alpha/beta. It's that:
a) We can't possibly field all the bug reports.
b) It changes too rapidly to maintain a real Q/A for beta specifically.
c) It really hurts our answer rate/percentage.
d) It burns out users that are capable of answering those questions.
e) Possible other reasons.
In most of the above cases, answers for beta are good and don't violate the rules at all.
In all cases, people that generally want to be helpful should be encouraged not silenced. As long as the answer isn't something like "They refused this simple patch to fix their stupid issue" it should be fine to leave answers for beta alone or even up-vote them if they're accurate.
EDIT: Addendum - We definitely should NOT have answers that advocate upgrading to alpha-beta to fix an issue.