A striking sport is probably even less conducive to bodybuilding.
If you're going to be punching - and I mean not one of those pussy ass cardio kickboxing classes, I mean really boxing or kickboxing - say goodbye to having a day for your shoulders, maybe even having one for your chest.
It will take you months to adapt to going ten or twelve rounds, and going just once a week is going to ensure only two things - you'll learn your craft extraordinarily slowly and you'll be extraordinarily sore from that specific workout because it's so unlike anything else you're doing.
Going from doing ten or twelve sets of shoulder exercises to throwing a thousand punches as hard and fast as you can is like going from doing ten hill sprints to running a marathon.
OP wants to do judo for fun so it doesn't matter how quick he progresses or how gassed he is when he's training... but if he ups that to even two classes a week instead of one, bodybuilding is going to become much harder.