I closed and voted to migrate this question to English.SE where it clearly fits as a grammar question. The question was locked by Community and closed by me, but it did not migrate. Is this a bug? I verified that I did indeed vote to migrate.
There was a bug due to some recent changes we made around "what's migratable?" checks between sites that I inadvertently introduced specifically for moderators. Previously, the check for "does the destination site had any of the tags on this question?" was bypassed for moderators but not normal users...that was no longer the case with the refactor.
Since a build last night, this is again the case and moderators again bypass this check.
Also, I went back and migrated that question, thanks for the report!