Sounds like some unionized grad students decided to go on strike on their own, without the unions approval. Firing doesn't seem unreasonable to me in that case,

Sounds like some unionized grad students decided to go on strike on their own, without the unions approval. Firing doesn't seem unreasonable to me in that case, and it certainly isn't "union busting" as Bernie Sanders said in the article, given that the school has an agreement with the union. If you never could get fired for striking, it would allow employees to hold the school hostage indefinitely while making unreasonable demands (not that the demands in this case were necessarily unreasonable, just that I don't think firing strikers is inherently bad).