The way I see it, that is Garcia's personality, I mean if he could just emulate Oscar when he was young, no trash talking but just wanting to fight the best. But Oscar protege is different, Garcia want's to get all the attention even not related to boxing. But hopefully him and Haney could go fight at 140 pounds in the future.
Everyone has a different personality, that's him, he is showing his real color, he is like Mayweather who loves to get the attention of the people, who knows that's helping him to gain confidence in the fight and probably make more money. We cannot judge though, he is still undefeated til now, so he deserved huge respect as a boxer.
That is also his way to market himself and his fights, being silent in the industry is no fun for sure as most fans wanted to see boxers who trash talks their opponent while also proving that they can do the talk inside the ring. As for Garcia, so far he can prove what he is saying but he should tread carefully about some things as it might be too much for him. For now, Garcia can enjoy his situation while having a flawless record at the same time because sooner or later, that record will be in a dangerous situation if he will fight Haney or Tank.