How I wish they at least tried with him on duelist first before getting icy T__T
riot doesn't want to "sell the spot" to players.
G2 bought the slot to field TGRD players, they are allowed to make roster changes but they can't put ShahZ in there because he was with G2 beforehand. Im honestly not sure exactly why.
I also don't think ShahZ would want to, he already gets enough hate and imagine if now "his org bought him a tier1 slot"