It's a very safe DUP seat of course,... and given the DUP constituency voting figures in the last U.K. Parliamentary general election in 2017,... 28,521 votes out of 48,460 with a 5.8% swing to the DUP,... it's very unlikely that he could be overthrown in a by election if he stood as a DUP candidate,... even if a substantial number of DUP voters voted for a candidate from another Unionist Party.
However,... what if he remained suspended from the DUP and stood as an independent candidate,... and against an alternative DUP candidate. ?
Arlene is a very shrewd politician, and so far most of the criticism about his behaviour has been directed at him personally,... and not at the DUP,... and the DUP has been very prompt to take action to distance itself from his behaviour.
Both Arlene personally,... and the DUP as a Party,... might have much to gain in terms of public relations and DUP voter confidence,... if they selected an alternative DUP constituency election candidate.
Arlene might also consider that there might be the possibility of further future bad publicity in connection with his involvement with the oil business,... she might also take into account that in the last election only 48,460 voters out of 75,657 voted,... and she might be concerned that many more voters might vote against him in a by election as a protest vote,... and if that happened, even if he won the by election,... but with a much reduced DUP majority,... that would be an embarrassment both for Arlene and for the DUP.