Abbas older brother dies

Arabic media is reporting that Mahmoud Abbas' older brother Atta has died in Syria.

Like Mahmoud Abbas (Abu Mazen), his brother had a nom de guerre - Abu Fayez.

Why do members of such a moderate family insist on having separate terrorist names?

And why did he live in Syria anyway? Wouldn't it have made sense for such a prominent relative to want to live in the Palestinian Arab territories? Or did he just consider "Palestine" to be part of southern Syria?