According to Mckenzie it changed in the new CBA. In old CBA, yes he would have to. In new CBA if a player is on your RFA list, he is exempt from this procedure. Since Colorado held his rights he doesnt need to go through waivers.
Thanks.. I thought that was the case at one time.
Edit: Here's a quote from the article in the OP explaining it..
Because O’Reilly spent the last three years in Colorado, he’s not viewed as a free agent who is joining a NHL team from Europe midway through the season. As a result, he does not need to clear waivers before suiting up for the Avs again.