He did protect his mates, probably as well as any other enforcer of the time but after 5 or 6 years, he didn't go looking for it nearly as much, he didn't have to and he didn't have a whole bunch of guys lining up to fight him.
If you look at his fight totals, his first 5 seasons look like he was out looking for fights with fight totals of 11, 34, 38, 26, and 26 then it drops to 15, 14, 9, 9, 11 the next 5 years. Having a wreck of a right hand had something to do with it also but he simply wasn't fighting as much, most guys go fast and furious through the first 1/4 of their career and then tail off and some are just consistent and others disappear for whole seasons.
Joe finished with fight totals of 5,6,4,4,5 his last 5 seasons. He often could defuse a situation just by "being there" ala
Nick Fotiu and Joe had the reputation, even in his later years of being deadly with that right hand.
I'd say he mellowed but he also matured into a decent player and realized he didn't have to fight 30-40 times a year to do his job.