It's not really about the numbers. The situation in Ireland is (relatively) unique in this regard. Most people in England who like football don't support (or also support) a foreign club. There are lots of reasons though that I think have been well answered in here a few times. You just did so in the post above that one.
Despite Pogue's unironic defensiveness about defensiveness, it was pretty clear (to many of us) that the OP was asking for these reasons to - in his own words ...
The fact he was then greeted by the general assumption that he was top reddingly asking the Irish lads how they dared to support a foreign team, some quite odd hostility from geebs and - in a zenith of weirdness - a poster making up a connection between Newton Heath's colours and the Irish flag to use as a credential as to why it's ok for the Irish to support United, just struck many of us as weird and OTT (....not OOT).
But both the reasons themselves and those for the defensiveness have both been explained and well and aren't particularly controversial anyway. Most people would support the closest 'big' League in the same position, Especially if most of their home grown talent was playing over there. You only need to see the rise in interest in La Liga when Becks went over there to see we English are just as culpable of it. He was on the front pages of the tabloids whenever he scored.
Yeah but they've got log throwing and shit.