Since the 3gs apple has only allowed you to upgrade to the most recent firmware.You don't get the option to download an older version?
Showing cydia means nothing, you can put that icon there with apple dev tools, doesn't mean it is actually cydia let alone a working one. Also if you read his site it says it is a bootrom exploit and it can be installed on the device its self which is impossible.think about this....
if all the guy is doing is baffling about this jailbreak WITHOUT actually showing proof it was jailbroken, don't you think that's a bit fishy?
In all his interminable talking did he once show us the Cydia icon, an indication that it is on a step to being jailbroken.