The MP has denied wrongdoing and earlier this week refused to step down. But his leader, political veteran Winston Peters, subsequently sent him home to sort out the mess and has refused to express confidence in Mr Horan.
Mr Horan should have stood himself down immediately until the matter was resolved.
His leader has done the right thing and has so far handled this matter well. He has fronted the media rather than trying to ignore the issue. And by only sending Mr Horan home rather than taking stronger action, he is leaving himself room should these allegations amount to nothing.
I have no problem with Mr Horan being on pay. He can easily work from home and is, of course, innocent until proven guilty.
But I do not agree with statements from Mr Horan that this is a private family matter.
Politicians cease to have privacy when they run for Parliament and any serious allegation is a matter of public interest.
MPs are bankrolled by taxpayers and therefore are accountable to the public. People must have confidence in MPs and it is critical these allegations are investigated and resolved promptly.
Mr Horan has been in the media spotlight a few times since entering Parliament, speaking out more recently over issues such as Rena, rotting railway sleepers, KiwiRail and foreign ownership of land.
But will his efforts to make it in politics come horribly undone?
If he is found to have done nothing wrong, then he should return to Parliament and put this behind him and those who have raised this issue must themselves face serious questions.
But if he is guilty of serious wrongdoing, then his political career has to be over.