"In Summary, there is no specific rule in an OBR based game to cover this, but in a FED game there is a SPECIFIC rule."
I don't see any such SPECIFIC rule in FED. Where is the language describing stealing signs as "not in accordance with the spirit of fair play"? You are still making a leap.
Obviously, in your mind, such behavior qualifies, but you are still intrpreting the rule to cover it. It is not specified.
In the minds of others it may be considered gamesmanship.
In the minds of still others it's just a prelude to a fastball in the ribs.
GB