Ian Royal It was being held for future failures to make payments...
I'd guess it's actually being held back for the next time Pompey fail to pay their players. PL won't give a toss about Watford. They aren't PL and nor are they a big foreign club.
The PL will care massively about one of their clubs not paying its debts to another football club at whatever level they are. Scuadamore recognises his league's obligations to the whole football pyramid.