1. The Sanhedrin was reestablished by a sage who was elected only by a minority of Israeli rabbis. Yet to be legitimate, wouldn't the reestablishment of the Sanhedrin require the votes of the majority of Orthodox rabbis? What if most Orthodox rabbis continue to refuse to participate?
2. You condemn the rabbis of Agudah and Shas as corrupt but how will you convince their followers to accept the Sanhedrin if you exclude their rabbis? (If you don't exclude their rabbis from the Sanhedrin, then their rabbis will bring their corruption to the Sanhedrin.)