Is "Trolling" Punishable?

Hey Brawl Community!
My name is Grenzo.
I'm very liking this website to be honest, but I'm still new.
Okay, lets get into the topic.
Today, I was playing Capture The Flag, like usual.
And, I was going to take the Flag from the enemy base, and I suddenly saw a Medic to heal me.
Luckily, there was no-one there, so I asked him for help.
I kept jumping in front of him so he knows that I need assistance.
Then, I realize he probably doesn't know what I'm saying.
So I press "T", and I ask him to heal me in chat.
Then out of the blue he says: "nu".
I reply with: "Yes! Please heal me!".
But he keeps on replying "No.".
So I asked him why, and he said: "Nah, I won't heal you, I'm a troll."
Then I told him I was going to report him, but I actually wasn't. I just wanted to see if it was gonna change his mind or not.
But, he still doesn't heal me.
So, I try to take the flag, and well.... I die.

My question is, is "trolling" or purposely not helping your teammate punishable?
Because, I feel like it should be. You're a medic for a reason, and that's to help your team. Not only throw cobwebs.

Underneath will be proof showing the dialogue.

Thanks for reading my 2nd post!
(I am not reporting him)
(I repeat, this isn't a report)
(If you cannot see the picture, click on it to ZOOM in...)
~Grenzo