I don't get this. He "sneaked back in". Moldova is not part of the EU, it is a basketcase of a former soviet state, created by a policy of divide and rule, from stolen bits of Romania and Russia.
If he had been deported, then his passport would surely be stamped, unless he got a fake uk visa.
I have never seen a UK visa, surely SURELY these are barcoded back to a central database of people who have been correctly awarded them?
This beggars belief!