I brilliantly argue in that thread that it is a deductible expence. Anyone who disagrees with me is obviously wrong. Except my wife.
But in case I'm wrong and you do claim it then so what?
You don't have to detail expences on your tax return. Revenue only look at a breakdown of your accounts in the one in a thousand chance of an audit .
And what'll happen then if they see you've deducted the cost.?
You can genuinely state that you thought it was an expence as you have seen nothing to the contrary and that the Revenue guide would lead one to believe it is deductible.
So, OK, the worst that'll happen will be payment of the tax due on that cost.