My potentially controversial take is that metagaming is neither good nor bad. A metagaming problem is really just some other problem that rears its head through metagaming.
You can metagame and be a good player. It's like doing improv with dramatic irony. If you're prioritizing the gameplay and everyone's enjoyment, it's a useful tool.
If you're using it for the personal advantage of your character, though... that can also be fine. Some old-school games, especially dungeon crawls, are like strategy games testing the players as well as their characters.
It's when there's a disconnect between how people are playing the game that you get problems. If someone wants to play a strategy game while others want to play improv, and they're not thinking about what kind of approach is appropriate and when, that you get issues.
Ok so I haven't seen that show in over 20 years, so I'm going off of hazy memories here, but as much as I like the guy, I don't think he was aligned good. He's kinda stupid, and would get talked into doing some pretty heinous shit when Arthur wasn't there to act as his voice of reason. I'd say he's either True Neutral, or Chaotic Neutral. Arthur is Lawful Good
I don’t think being dumb or gullible precludes you from being good. His heart is in the right place. In a fictional world of super heroes and villains, I’m unsure if he’s operating within vigilante laws. I think he’s dumb enough to not know what they are and attempt to follow them. If he was willfully ignorant of the law it’d push him toward chaotic. So I’d say he’s definitely neutral.