You can not say people excuse one sin, but does not excuse another, That is not being honest. Pharisees justified divorce and adultery, They justified lust, they justified all kinds of sin. That was the Pharisee way.
God never told Israel to kill gentiles or kill anyone who does not agree with them, The Pharisee made this rule up themselves. It is called a false religion, It is done so you can tell God. Look at me God, See what I am willing to do for you. I am not like the sinner.. thank you God..
Jesus called out the Pharisees for their sin in all kinds of ways, how they justified their sin, Saul was one of them, so he accused saul of those things also.
Saul went from being a very wealthy man, A man who was high in not only roman culture but as a Pharisee, a man of power in his own jewish society, He had power, prestige and money, all things any man would desire as a Pharisee, (in fact, the truth is paul had no reason to covet any mans things, He had everything he would ever want, and if he did not have it, he could certainly get it.)
to a man who gave up everything, Had to work to earn his money, and was considered by his nation and the romans of being nothing. Had a thorn in the flesh given by God. and many other things he lost.
I personally can see Paul getting jealous of people. missing what he had, Satan could use this against him, His own flesh could cause him to question things (especially in the beginning of his Christian walk) and if he tried to appose these temptations by the law (the flesh) he would have realized real quick he was in trouble.
Sometimes you just have to think things through, and they make total sense.