Danzo: "Boy, don't think that you can do whatever you want with some strength, Konoha..."
Inuzuka Meiya: "Shameless old thief! Shut up! If you have strength, you can do whatever you want. I can do whatever I want, what can you do to me?!"
Inuzuka Meiya discovered that he was born with a "Youth Training Manual". After discovering that wonderful and invincible ability, he decided to do whatever he wanted in this ninja world where strength is paramount. If you have strength, do whatever you want. Why hide it? Pretending to be a grandson?