WWL issued a statement that it was abhorrent or something to that effect. I don't think that simply issuing a statement would resolve the situation for Seth - he needs to know who did it and what has come of it. What if it was a producer or manager he works with?
I don't think there needs to be some public shaming, that's another can of worms. But internally, WWL needs to find out who did it and they need to share with Seth their findings and what they're doing about it. Just imagine that instead of someone attacking Seth with the offensive slur on the employer's twitter page, they jumped him in the secure building and knocked him out - but he didn't know who did it. Certainly we would all expect the employer to investigate and if they were able to determine who did it, the targeted employe would certainly expect to be shared that information and what was going to be done about it. It's no different.