Daren Ganga is not even a ODI Player. His strike rate is too bad that he could not find a place in the ODI team itself . No point in even thinking about him for a 20-20 format.
Collmore is a very old fox who is less impressive these days. And when it comes to 20-20 age does matter.
Anyway , when the Big 3 (from Indian Team) are forcefully asked to withdraw from the selection , there is actually no surprise that these two did'nt figure out in the West Indies initial squad.
WI has decent chance of success in the 20-20 format with it's power hitting heros (Gayle,Samuels,Smith).