I agree with Tom! Complete and utter, murdering scum.
The mouthing off about the flag of a "foreign country" (which is what set off the Sinn Féin supporters) is insulting people well beyond the sort of Tricolour-brandishing Shinners who turn up at election counts, and is the sort of thing that even the DUP now avoid saying in public. The nearest analogy in a GB situation would be of a mainstream politician implying that second-generation British Asian voters were foreigners.
But then Tom Elliot has form when it comes to insulting his neighbours; a few years back, when the Fermanagh county Gaelic football team were beaten in the Ulster final (background: Fermanagh are the only county in Ulster never to have won the Ulster provincial title, so reaching the final was a big deal for them), he was quoted in the local paper the following week as being delighted because it put the team's (overwhelmingly Nationalist-voting) supporters back in their place.