It is a "cheat" imo, because the salary cap is already too easy, way too easy. In multi-user franchises people can see that they are the only user online and do crap like this to further manipulate the already way too easy salary cap with zero risk of having anyone else sign the guy. The CPU is too stupid to swoop in and ruin this method and that is a problem.
Again, if it is an agreed upon practice - go for it - but as I play in "sim style" leagues where the cap is already too easy - we want more options - ie the toggle on/off waiver wire and user/commissioner "controls" on the salary cap. That way we can have a league that more fairly replicates the salary cap preventing recreations of the "pro bowl" teams.
We want to test not only our ability to play the games, but also our different "team building" strategies in an environment that is more restrictive and therefore more challenging...