Pardon my noob-ness, I don't know much about different capacitor types
My job is to educate about capacitors and I meet people who have been engineers for decades who learn something new. So everyone is a noob. Capacitors are the most misunderstood "simple" device.
Is there any reason, other than form factor, that we couldn't use an aluminum electrolytic for this purpose?
My guess is that for this application, form factor is why an aluminum electrolytic wasn't used. Wet-Lytics generally have a pretty tall height associated with them, so that would mean a non-stackable shield.
The reason for this particular cap is probably because when the GSM radio goes active, it needs a sudden surge of current, which the dry-lytic (tantalum) provides.