Yea, beginner on a 9' boat down Westwater... not a good idea.
Take someone like Stonewalker up on their offer. I would recommend doing it on a bigger raft before attempting it on your own. In fact, I think the BLM requirements are that you have to have experience with someone that has been on it before you can go as a leader.
I'm not saying a 9' won't work... but as others have said, Westwater is not a beginners or even a low class river. I've been doing it for 6 years now and I wouldn't dare take my smaller (14') raft down it unless the flow as like it is now in the 5k range.
If you don't get on it this year, we will be going on it a few times next year and if you watch here we usually have openings and I throw the invite out for people to join us.
Go look through the posts and you'll see videos from me and a few others on here of our floats down Westwater this year. Or search on YouTube, there are a bunch on there.
River Use Stipulations - Westwater Canyon
lists all the requirements you have to meet to pass the ranger's inspection.
All of that said, its a damn fun piece of river and I love it. I would go every weekend if I could.