Play your role or risk punishment.
Title is TLDR.
In the case of this Singed, no he was not playing support. He was playing Duo Jungle. Is that itself bannable? No.
The thing that made it bannable is that his team did not want him to play Duo Jungle (even if claiming he's support). They wanted him to play support. If he had done so he wouldn't have been banned. If you're going to go off meta to the point of which it's hard for people to tell if you're still playing your given role it's important that you get the OK to go ahead with that in the game lobby BEFORE locking in. If you don't, you're at risk for being banned.
In the case of playing support you are expected to: • Provide ways of keeping your team mates safe (CC, Vision, Body blocking skill shots, Tanking, Healing, Team Buffs) • Find ways of earning gold without taking it from your team mates • Provide opportunities for your team to secure objectives and kills (Poke, Engage, Wave mitigation if necessary - zz'rot)
Duo jungle can work Having 2 supports can work Having 2 mids can work etc. etc.
but riding those lines without checking with your team first IS reportable and could lead to a ban. You're not likely to get reported if you win but that doesn't change what you did. Win or Lose you're still putting yourself at risk so it doesn't matter if you have a 75% win rate, 80% win rate, Any% win rate. You're still breaking the rules. You can still be punished if your team doesn't agree to what you are doing.