First off, it would take many generations and keeping whole clutches to do so. The problem here is, how many keepers have produced generations????? For any reason, muchless for attitude.
Secondly, attitude is both inherent and learned. Very simply put, you and pea off a monitor and it will go ballistic on you. The learning part is, they remember who pea them off. I have seen this with many species. An example is George, hes my oldest lacie male. Hes a bit of a lover, then comes food. Or food then love. He could give a crap about other monitors. But if one bugs him enough, he will go balistic on them, with serious intent. But only after enough proding. A lot of proding.
This goes for people. Most monitors are very tolerant, but most people keep bugging and poking and picking and do not leave them alone, then the monitors goes nuts on them. You cannot blame the monitor. It has to go nuts, it has no other option. Its that or internalize stress and die.
Also, keepers would rather breed for goofy color morphs and zig zags and all such things.
Besides, monitors are in most cases(99%) very very nice and friendly curious animals. Its the people who mistreat them, then blame the monitor. Sorry for the editorial, hahahahahahahaha
Anyway, in most cases bad attitudes(like mine) are learned and not genetic. Cheers