It's not a proper 'training'. How do you implement it ? In addition to training ? It's hard to balance in gameplay terms.
Nobody (or close to) would never take the risk to increase physicality. So let's say your suggestion is about reducing a player's physicality. We know little about how physicality works, the stat is hidden and the benefit of it apart from the drawn fouls is obscure. It possibly helps in defense but for the reasons I have just listed it's difficult to gauge.
More importantly, I don't think that's something you can train or change when you are a grown-up. Artest's exemple is not good. He has or had bad temper, was aggressive, easily lost control of his nerves, couldn't control his emotions and was a bit of a lunatic off-court primarily and received counseling for that and if I remember correctly since he was a kid. It is not basket-ball related. Actually, I think basket-ball helped him a lot by letting some steam off and that his intensity on court was welcome by his coaches.
And I don't think it is what the hidden trait 'physicality' in BB is about anyways. I understand it as how a player will play with his body, with checks and trying to outmuscle his opponent. It's very different from not being level-headed. I don't think you can change it past some point, you can't learn it or be the same player without it but with experience, you can use it better.
In game terms, there are truly some problems with this trait. It's hard to see when it is doing good and I feel that in addition to drawn fouls, it may help in defense. It's obvious when it's harmful but we have no control over it, I'd like individual instructions to set defense intensity for example.