From the article: "Other researchers have explored more noxious ideas to drive animals away from people, including paint balls, rubber bullets, squirt guns, specially trained dogs and park rangers swinging streamers attached to hockey sticks. Some of these are effective, some are not. Some animals learn to avoid human areas but others just learn to avoid rangers with hockey sticks. And “how much does a paintball hurt a 500- or 1,000-pound animal?” asks Robert Found, a wildlife expert at Elk Island National Park in Alberta. “That’s not enough of a stimulus.”"

I think using an unloaded double-barrel shotgun to aim a bottle rocket at a coyote might be successful at scaring them if a paintball didn't do it.