No, the comments are not in themselves sexual assault. However, the activities Trump is bragging about — barging in and kissing women he doesn’t know without getting their permission first — certainly is.
Let’s see if we can put this in terms you can understand. Let’s pretend that Trump was confessing to a murder in a “private conversation” with someone. The conversation itself is not illegal. However, the activity he’s bragging about certainly is. See how that works?
Yeah, that headline could have been better worded to indicate that the “sexual assault” was the topic of the conversation, not the conversation itself. However, brevity is a requirement for headlines, so important context is sometimes missed.