The guidelines are a bit vague on what's acceptable. Your logo does pop out more than their example, but I can't imagine it getting flagged. When in doubt, ask policy@udemy.com - we're just fellow instructors here and can't really give you a definitive answer.
To clarify though, you aren't *required* to have a watermark. They're just saying that if you do have one, it should be unobtrusive and not try to direct students away from the site.
