You can't stop someone investing money into a business. If they stopped sugar daddy chairman then they would just become the £1 million shirt sponsors.
I believe the way to go is what they are trying now, checking that regular payments are being made on the tax and VAT
Yes, I totally agree. THe expense that never seems to get paid when clubs hit trouble is the VAT and IR, which is mainly due to the size of the bills. In effect, if they are checking these are being paid, at least they are limiting the debts that can be run up.
The one other thing I would do, is limit the ways that directors can put money into the clubs, directors loans seems to be the other major way in which debts accumulate quickly. thus, if directors do want to put money in, they have to donate it!