Isn't the rule meant to be pretty restrictive? If a rule like this isn't "restrictive", then what's the point of having it?
(Edit: Oh, duh. I guess the point is to protect the noobs, like you said. But consider the implications..)
A separate, less general thought:
Say you have an open league team in Petco. The rules tell you, in effect, that you have to draft a Frank Gilmore or somebody and play with a $79.2 MM payroll against the rest of the league. If you want to disincentivize the use of low-IP stadia, while effectively incentivizing (word of the day) the use of high-IP stadia, that's fine. I wouldn't call that a desirable goal.
The net result is that you weaken Petcoish teams while relatively strengthening others. Come to think of it, wouldn't this also push the pitching/offense balance more toward offense by forcing crappier pitchers onto rosters? Maybe not, overall, because the Gilmore Requirement would leave Petcoish owners with less money to spend on their offense, which brings us back to the beginning of this paragraph. Please do not allow yourself to get caught in an infinite reading loop.
Note: The teams I hate to play most play in low-run, 3B-friendly parks like Petco. I'd benefit from a high floor, which would make these guys spend less on their good players than they normally would, while I draft exactly as many innings and spend exactly as much on pitching as I would have before.