[jpthomas]

The arabic script is written and read from right to left. I'm wondering whether the slant could be a side-effect of a native arabic speaker/writer contending with writing in the direction opposite to which he/she is accustomed.

[JenB]

I'm wondering whether it might be from a right-handed person writing with his left hand. Try it sometime; the writing tends to slant, you have to work hard to make it legible, and it looks very different from your usual style.