The "vegan meatballs" headline is misleading, probably deliberately by the look of it. The company never said that these were vegan meatballs as far as I can see and I don't agree that this is implied by the fact that they have stated that they make plant based meat. As far as I know, the company has never declared itself 100% vegan in every product?
So one person verbally made a mistake about whether one product contains cheese. It's not like they put it in writing as an official policy, and then broke that, which would be a different thing altogether. Mistakes can get made in a verbal conversation.
This company will replace meat burgers, help end factory farming, and reduce animal suffering and deaths thousands of times more than most vegans ever will.
Probably 5-10% of their customers are vegan, but 90-95% are not. They are going to be primarily interested in keeping 90-95% of their customers happy than 5-10%.