I'm kinda hoping you meant 'delay target permanent', not 'delay all opponent's permanents'. If it was just one permanent, I think that would be fairly reasonable, although we'd have to work out what happens to stacks of permanents as well as shields that are delayed. It would be ridiculous, for instance, to delay an entire stack of pillars so that they didn't produce quanta, but delaying one out of that stack would be fine.