I don't see the difference between offering someone 500 gold to become an infiltrator, and offering someone 500 gold to not attend a tournament. Neither one is a punishment.
Becoming an infiltrator is something that many people enjoy. It is perfectly reasonable to assume that someone may wish to become an infiltrator in the realm, but lack funds or encouragement; the offer of gold will just give them the necessary push. Making that generally to the realm as a whole ensures that the IR of a specific player is not infringed (I would look at it differently if a region Lords tried to push his knight specifically to become an infiltrator).
Attending a tournament, on the other hand, is something that you do if you want to and don't if you don't want to. There is no purpose to the offer of gold other than to violate the IR.
