““boat parked in driveway for weeks””
If so, the cop would’ve come out and mentioned that, e.g. “there have been complaints about your boat blocking the street” or ask him to move it, or give him a ticket or something similar.
Since that did not happen we can conclude there was NO reason.
We still don't know if there is a "backstory" here (prior contact, etc.), but this statement by Mr. McComas would seem to indicate that there is: "McComas briefly complains “you guys have done enough to my family” and calls the police “corrupt.”"
See: http://www.pressdemocrat.com/news/4299394-181/video-captures-rohnert-park-police?page=3