When a user's rep gets bloated because of serial upvoting, and as result the user is given the association bonus, shouldn't that association bonus also be reversed in case of serial upvoting reversal?
Yes! The associate bonus which was acquired wholly and solely through serial upvoting should be revoked when the serial upvotings are reversed. Provided after the reversal the rep drops below 200.
When the cause itself was not legit and was curbed/reversed there's no point in letting the event/association bonus be left standing. It should be taken away.
Ok let the badges (if acquired as a direct result) be an exception. After all badges don't earn you any privileges and/or extra benefits.
Bit extreme but worth considering:
The votes given on other sites using the benefits of that association bonus should also be reversed.