That'd probably work too. But it's extra when you have stuff like le monarque, wish-ender, Divinity etc not needing any extra steps to proc their champion mods.

For usefulness and convenience and probably ease of coding, it makes more sense for it to be all the time. It kind of makes sense for an alt fire mode to be the source though. This would possibly allow double coverage with 1 type of champion mod in 1 mode (from a seasonal mod) and 1 as default in the other firing mode I’d even throw riskrunner out there to have overload rounds when arc conductor is active.

They've never allowed any weapon to have more than one champ mod. Anything that has it's intrinsic mod can't be changed even if there's other mods for that weapon type in the seasonal artifact. It's fun to hope though. The alternate fire modes wouldn't really work. (Scenario) you're using vex mythoclast and You killed every enemy in the room with except a champion, you don't have the alt fire mode charged up and then you can't stun. Now you're doing crappy damage. Putting the mod on the base weapon no alt mode makes it much less complicated.