Nope, not good enough...
Federal law--33 CFR 159.7 "requirments for vessel operators" says (and btw, Types I and II are CG certified treatment devices...Type III is a holding tank): " (a) No person may operate any vessel equipped with installed toilet facilities unless it is equipped with:(1) An operable Type II or III device that has a label on it under §159.16 or that is certified under §159.12 or §159.12a; or(2) An operable Type I device that has a label on it under §159.16 or that is certified under §159.12, if the vessel is 19.7 meters (65 feet) or less in length."So just securing the thru-hull for a toilet plumbed to only discharge directly overboard ain't legal anywhere in the US (not sure about Canada). He either has to remove the toilet from the boat altogether, or install either a tank or a treatment device. Whether a treatment is an option, or holding is required, depends on whether the waters you're in have been designated "no discharge"...and since almost all SoCal waters are ND, he'd prob'ly have to install a tank to make his boat legal.However, enforcement is another story. In coastal waters, he MIGHT be able to get away with just tossing a portapotty onboard for use while inside the "3 mile limit"...but that would be at the discretion of the local CG and state enforcement agencies.