By blurry you mean out of focus or motion blur? I’m gonna assume it’s depth of focus that’s missing here.
2.2 seems a bit shallow for a moving target, I’d close to about 5.6, bump the iso up one stop and the flash should go up a stop or a stop and a half. That’ll give you enough depth to work with.
If you're paid upfront then go by all means. If this person is aware there are gonna be photographers and will bring their own chances are this person doesn't want to buy what's offered.
Some of the other photographers may get pissed, but business is business. They should get pissed at the organizers or plainly just choose not to participate under those terms, I wouldn't.