There's nothing inherently "not good" with switching jobs, no. There's also nothing inherently "good" with switching jobs, either. It's at best a neutral action

There's nothing inherently "not good" with switching jobs, no. There's also nothing inherently "good" with switching jobs, either. It's at best a neutral action. However, given what he said he wanted to do, the argument is that he didn't do any of that, and just took the next job that came along. That the company he took the job with doesn't have the most ethically or morally clean reputation doesn't help the situation.