Layne Norton is a smart guy but honestly, he looks like shit. If there's a juicer at the gym using a very low dosages of PEDs, has mediocre genetics but looks fucking spectacular then I'm going to listen to him. Sometimes you need to put down the beakers and test tubes and stop being a pussy, with all due respect of course. He only looks good when he's dieted down, coloured, standing in professional lighting, for no more than a single frame which is taken at an epic "MySpace" angle which would compliment anyone fabulously. That being said, lets forget about him and his following of nitwit cocksuckers. They're a bunch of straight edge emo's who need denounce anyone who uses PEDs or goes against the Wise One.
No cardio is needed, but I think it does help a lot more than just cutting calories. Do a little of both. Like others said, it does wonders for the metabolism and cardiovascular system. This is why I still do cardio primarily. Also, I can be a bit of a glutton and not have to worry so much about nutrient partitioning.
If you use thyroid medication and insulin, you can ABSOLUTELY and WITHOUT A DOUBT gain muscle and lose bodyfat. There's 24 hours in a day!!! Optimizing your body to partition nutrients to their maximum efficacy, you can lose fat in the morning through low intensity cardio, then eat an adequate amount throughout the day to become anabolic. Ta-da. It's not rocket science.
If you eat a caloric surplus there is a chance of putting on some adipose, of course. But if you want to take it to the next step, throw some ECA into the mix. If you want to use PEDs that are more effective then use clen and T3 (or just T3 like I do - I don't like fucking around with my cardiovascular health). Now top it off with a bit of timed insulin and you're golden. If you're on AAS, you should have no reason not to be pretty close to "beach-ready" all year-round.
Honestly, I'm not the smartest or most genetically gifted individual out there. But I spent a good deal of time reading, training, prepping food and eating. I don't look spectacular and I'm no scholar, but I look great and I keep an open mind. When I get back on the sauce, I will look spectacular. I've learned so much through my own little fuck ups. A lot of people just fuck up but don't learn from it...I don't know why? Even when completely natural I was able to lose fat and gain muscle. I know friends who have too. I don't know why this myth has been perpetuated to no end. It's not the most efficient way of going about things, but if you're at that awkward stage where you're 10-15% bf, can't really cut and feel small or can't really bulk and get husky... just recomp. Eat clean and do cardio, but don't shrivel up. Heck, maybe gain a pound or two of muscle. If you're on drugs, that shit should be a walk in the park!