Sounds to me like the Arab writer is exaggerating out of hatred for the Franks. They were not much liked back then for obvious reasons:
The Islamic world generally viewed non East-Med Europeans the same way the Greco-Romans did; as barbaric savages, even when this was arguably unfair. I get the sense that they often exaggerated how bad they were. You can sometimes see the biased contempt oozing off of their texts like this one.