Both approaches work, it depends on which style can work for you better. I'm not going to say Luca's way is wrong because it isn't and he has achieved more than anyone on this forum could dream of, but at the same time he's not Rossi. So I say, experiment with both and see which one you're comfortable with. Some MotoGP riders keep 75% of their weight on the outside peg others keep 100% on the inside peg like Toni Elias. Experiment and do what works for you.
Dunno, keeping the majority of your weight on the outside peg sounds too tiring, let alone your giving away a very useful steering tool (Ken Hill:for corners that you need to brake for, loading the inside peg at the rate you want to turn in). I can't say it's wrong, Luca is a potent rider, it just feels wrong.
I do both, and which I do for what corner is largely dictated by economy of movement. Using Road Atlanta as a track many are familiar with, for T10 I generally get most of my braking done while pinched in the center of my seat - because I've just spent the last half-mile tucked in the center of the seat already. For T12 I'm already set up off to the right while I'm braking, because I was off to the right while coming over the hill and I'll be off to the right during the actual turn. Don't concetrate too much on what someone else does. Use their advice to get ideas on what you might want to try, but don't take it as gospel and definitely don't get too caught up on specific numbers like "30% of weight on inside arm". Control the motorcycle in what feels like the most natural and comfortable way to you - that's the way that will be smoothest, fastest, safest and best, for you.
Doesn't what he describes about pressuring the outside leg and the inside arm sound like what CCS calls pivot turning? I'm not a huge fan, but I can see the pressure on the inside bar tends to keep the bike turned in and leaning. I run into a problem weighting the inside peg trying to lean past a certain modest point. Yeah, I'm slow, but I don't know if it's because I can't open my hips well when weighting so much on the inside peg or if I don't feel locked and trust my base standing on an inside peg as the bike tips over. I am interested in relistening to what Ken Hill says about turn in rate and weighting that peg.
Search for his "Turn in point, turn in rate" podcast. Then listen to every single one of them, huge amount of info.