Playing cards "on someone" vs "on combat"

[Mathgeni]

Last week playing Steampunk, a player used a card that said nobody else could play cards on the combat. I proceeded to play a curse on said player as I viewed the curse as being played on the person and not on the combat as it wasn't a one-shot or monster enhancer. Another player declared that this wasn't legal because it was "with the intention of altering the combat." This week that same player defined playing a curse as "on the player" to which I brought up his previous statement and being inconsistent. He adamantly holds to the belief that the situations are different because of the "intent" of my curse in the previous week.

I hold that a curse is "on a player" regardless of the intent because it is not a card played directly into the combat scenario.

Could we get some official feedback on this general situation?