Are you suggesting human intelligence is unique and the upper limit for intelligence? I mean we can argue about the difficulty and timeline for achieving human level artificial intelligence, but it seems unlikely that it's impossible.
So, if you're not worried about the extinction risk of God, why should you be concerned with the risk of "superintelligence"?
It's more of an inevitable consequence (over an unknown timeline, granted) of the assumption that human intelligence is not some kind of absolute limit, and can be reproduced in a non-biological system. I admit that is still an assumption, but the opposite seems harder to support to me, though we're all admittedly guessing here.
Once you make that assumption, then yes of course it follows that the 'beyond human intelligence' would be able to do all of the things that human intelligence is already doing. Namely, science, mathematics, developing AI systems etc.