Likely the case. And if you think about it, it's a bad match as well. Raw is a perfectly fine diet for a healthy dog. When they get sick, you typically switch to cooked meat and rice though, because the bacteria can become more of an issue. With people who you will be seeing in therapy work, a good number of them will be sick or have compromised immune systems simply due to age. Hospitals and retirement homes are VERY careful about food handling and preparation, as well as cleaning constantly, and to bring in a dog with a raw diet would be asking for trouble for some of the citizens. It's a preventative measure that is easy to understand and a huge liability if something does go wrong, and you don't want to be on that end either.
If you don't want to switch your dog's diet you can change what type of work you do, too. If you're okay switching your dog's diet then there's no issue on that front.