hussie wasn't paid 20k to draw the two trolls getting killed. two people pledged 10k each, the reward for which was your character becoming a canon character in homestuck; however, they failed to fulfill their pledge, so they were drawn... and killed right after, iirc

10,000 guaranteed the characters survived one panel

A 100,000 pledge guaranteed more than one.

So yes, he was paid.  I know the wording on the wiki is confusing.