No, the casters weren't banned.
Free Hong Kong, Boycott Blizz

It took Blizzard nearly a week to decide they were going to ban the American University Hearthstone players that held up a "Free Hong Kong, Boycott Blizz" sign during a recent tournament event. A week to decide that they were going to ban the team. It took them less than a day for Blizzard to issue a ban against professional Hearthstone competitor Blitzchung after he voiced his support for the Hong Kong protests.

Today, Blizzard issued a ban against the team that already imposed a self-ban on themselves. Not only that, but Blizzard did not issue a ban against the two casters that were hosting the collegiate esports tournament.

Much like the reduced ban issued to Blitzchung, the American University team was also banned for a period of six months. At least they're trying to seem consistent (so long as you ignore that they didn't ban the casters)

One of the American University students, Casey Chambers, posted the email about the ban that he was sent today from Blizzard.

"Every Voice Matters at Blizzard and we strongly encourage everyone in our community to share their viewpoints in the many places available to express themselves. However, the official broadcast needs to be about the game and competition, and to be a place where all are welcome."
Why did it take Blizzard a week to issue this ban while taking less than a day to ban Blitzchung? Why were these casters not banned while the casters present for Blitzchung's event were banned? Why is the rule that Blizzard keeps citing so incredibly vague and its enforcement seemingly so inconsistent?

Blizzard seems to have only done this so they can keep trying to push forth the idea that they didn't ban Blitzchung because of China, but because of the rules. Sorry, but nobody should have bought into that reasoning then and nobody should buy into that reasoning now. By all means, Blizzard, keep digging that hole. You'll get to China eventually.