They can only strip his accreditation, which would be both meaningless and strange. You don't need a ticket to write about the NRL, ony to attend press conferences. And even then I wouldn't think it's essential. If everyone needed accreditation then this website wouldn't exist. And it would be a PR nightmare too. The NRL would need to employ another dozen spin doctors if they are going to get involved in any more weird stuff.
And lets be frank, if you can bash a woman and keep playing, there is no way the NRL would try to punish someone who doesn't even work for them for speaking against violence and taking a stance that most footy fans seem to agree with. Some people are getting caught up in the "......but Buzz is a grub rah rah rah" angle. Not many, but some. Most people seem to be thinking the perpetrator of this crime is the grub and the punishment (or lack of it) is disgusting. .