Is it just me, or are the Muslim factions a bunch of backstabbing traitors?

My Turkish campaign was going excellent, I had secured modern Turkey and then some, and my only issue was the unpleasant Crusade called on me by the French to boot me from Constantinople. No suprise, I was ready for it and handily fended off no less than three sequential attacks by the Byzantines after I took Constantinople, or Istanbul as I like to think of it ;)
Thus far superior archery has reduced most Byzantine attacks to loads of corpses before or shortly after they break down the gates. Slavic mercenaries seem to be effective defensive units and can handle anything the Byzantines care to put in a tower/on a ladder. My own general will usually take good care of any enemy cavy rude enough to knock at the smashed-in gate.

Anyway, suddenly, out of the blue, a full stack of Egyptians marches into southern Jerusalem. I know what that means. The AI never marches a full stack into your territory for no reason.
Those pigdogs want my holy city!

Anyway, this was followed by a horribly bloody battle. Fourtunatly I had enough cash to load Jerusalem with mercenaries after I saw that army coming my way. I was immidiatly impressed by the scope of the Egyptian army. It was not, as with the western armies thus far, composed of %90 spear militia. It had tons and tons of mameluk archers and other unfriendly units, and here I was with one measly unit of javaliners backed up by lots and lots of moderatly inferior cavalry. It took a while, but clever use of skrimishing horse-bows and a few Siphai charges beat the dogs back, at the cost of half of my forces in the city.
Now Im frantically trying to reinforce both fronts while, at the same time, keeping the Ruskies from exploiting any weakness in my northern front.


Anyway, to cap this all off...
Is it just me, or does it seem like the AI is just a TAD overeager to betray you? I mean, I can see the Byzantines breaking our alliance. Im the Turks after all and Im squatting on land that was theirs for a thosand years or so.
But why would the Egyptians chose such a low tactic as trying to backdoor a fellow Muslim ally while he was fightint the much-hated Byzantines? It seems like the AI (as far as Ive noticed) doesnt betray other AI's nearly as much as it does me.