That is why the work account should be separate from the personal account. While there might be certain kinds of work where that might not apply (actors?), a ministerial account should be mandatory for continuity through cabinet shuffles and changing governments. In fact, it should be prohibited to use an account created before becoming a minister and which might continue to be used after losing your portfolio.

I'm not sure how I would have decided this case, but I would tend to side with Levant's position in principle. If you're using it in an official capacity, then it's de facto official.