And Bir Tawil is just a worthless desert, but Hala'ib Triangle is mostly fertile land with a sizeable shoreline, so why would anyone pick the worthless desert over it instead?
Well, strictly speaking, either country could decide to claim both areas, it's just they believe that by doing so they would be lessening their chances of their claim over the preferred area succeeding. So it might be more accurate to say "without weakening their claim" instead.
To you perhaps, but outside of your imagination?
“members of the Ababda and Bisharin tribe … carry goods, graze crops and make camp within the sands.”
- good military outpost - possible mineral rights?