according to Colm MacNamee in 'The Wars of the Bruces (1997), p186-7, 'Having captured the Isle of Man in 1315, he (John of Argyll - fighting on the side of the English) sent the Bruce's garrison led by Murtagh MacKennedy to Dublin, preferring to see them behind bars in Dublin Castle rather than release them for ransom'.

Did John of Argyll then garrison Mann? I don't know...

Another 'veteran of resistance to the Bruces' was Dungal MacDowell. 'He had been sheriff and constable of Dumfries from 1311 to 1313, and then as commander of Rushen he had held out against Robert I for six weeks.'

So there may have been several different groups of Scotsmen on the Island in the 14C...

I note too, a couple of the early Rectors of Andreas:
Makaboy 1270
Cormac 1320

McBoy/McBooy/McBoyd seem to be quite common in Kirk Michael baptisms in the 18C, which is probably a very tenous connection!