Hide Unlicensed Account in Microsoft Teams Search - OnPremise Exchange
Solution 1:
If you mean you're running a hybrid of Exchange 2016 and O365, I would say unfortunately the ABP/GAL is the idea. As Teams searches in your Azure Active Directory, the unlicensed users could also be searched. So you should enable the ABP for the Exchange online to narrow down the scope of searchable items in AAD.
But note if you deployed the ABP on those 200 who have Teams enabled, the other 100(if they are UNLICNESED) synced mailboxes could be disappeared from your address book.
Best regards