IMO the cardio will help his legs.
I just started light cardio, 15-20 mintues, 4 times per week. I'm not losing any weight because I'm eating big. And I'm reducing my leg training a bit.
And for the first time in my life, the outer quad pops out. And my calves have improved a lot. Even something minor like 20 minutes slow uphill treadmill at 6.0 at 2 mph, is making a huge difference.