If a dog is kennel shy..it means they may be perfectly friendly (or not) outside the kennel, but once inside they won't come out freely. They may bite you if you reach in. Most of the dogs we do like this are fine once you pull them out of the kennel. For those dogs we leave a slip lead on them and attach it through the grate on the front of the kennel door and attach to the hardware. That way we can pull them to the front without having to reach in. I muzzle very few dogs. I WILL muzzle if need be, but I try many techniques before resorting to muzzling. Muzzling a dog can actually put them on the defensive and make them worse. A good groomer will teach you how to position your body to keep yourself safe. A good groomer uses both front and back nooses on a table...not just a head one. That means the dog cannot fall or jump off a table and it leaves you with two hands free for controlling the situation.
There is a Groomers Forum on the web that would be an awesome place for you to ask all these questions. You can read A LOT and learn much from other posts.
I think this is a link to the one my groomer likes to use.
http://www.groomerslounge.com/