but still the last TB can game this function and knows it a priori.
He can "game" it by spending (hundreds of) thousands of decrits. Then he must do this again at the next CB point.
The attacker only needs to target clustering his SHs in a consecutive order
By spending hundreds of thousands of decrits. And then what, denying SHs consensus? We've gone over that.
and then once he has all in a CB or nearly all,
With your pompous presumptions that 100% consensus won't be reached each CB.
Sure if you introduce fatal flaws in my design, fatal attacks could be found. Luckily, I know how to design a better system than you.