While we're here, you can also add:

$timeline->setQuoteRef($url->getMonogram());

That should make the "Quote Comment" action available from the dropdown on the right hand side of comments in the timeline correctly quote comments like this:

In Uxxx#yyy, @some-user-name said:

Without setQuoteRef(), the link to the comment won't populate (I think the text just falls back to something generic). You can test this by quoting a comment.