Is this airdam legal for IT?

[Greg Amy]

Air Dam/Spoiler shall be attached to the body. (shall: will have to, is determined to, or definitely will: You shall do it. He shall do it.)

Rules do not state it must "only" be attached to the body. As long as it's attached in some way to the body (whatever definition you care to use for that) it's legal.

The Roffe Corollary.

Don't see how you win that protest

There is no protest on this issue. Never has been, as far as I know. And I'm willing to wager there likely never will be.

On edit: If, however, someone were to decide to get a bug up their ass and try to make a point by protesting this (and/or trying to change the rule), and should they protest anyone besides me, I'd be glad to spend my own time and money to assist in the offense. In fact, if someone really wants to protest it, I'll be glad to accept that challenge with no avarice toward the person doing it.