So presumably they'll be deepstriking next to enemy armour and causing havoc? I can't speak for how effective or points-efficient it'll be, but who cares about that when you can have a cool commander!
Also, I tried running through the Tau Xenolexicon for your Tau names, and here's what I got:
Ra = Wrong
Meses has no translation, closest I can see is Mesa = “To mark” or “To Identify”
So... Commander Wrong Mark? Misidentified? Disguised?
J = To Relfect, reverse
Karta doesn't exist, but Kar = Correct and Ta = Soul
Reverse correct soul? Corrupter?
B = Shepherd, Guide, Basic
Guide correct soul? Savior (in a religious way)?
Nel doesn't exist, but N = Second and El = Hero/commander
Basic Second Commander? I'm not sure.