Shouldn't be done. I'm sure they wouldn't really be bothered by eachother (other than young sturgeon never stop moving...) but the warmest water sturgeon is a Sterlet and they should NOT be kept above 72*F and for the longevity and happiness of the sturgeon shouldn't be kept at that temp for long periods of time.
They need cool water and LOTS of oxygen. Cool idea, but I wouldn't try it. I have mine in with my coldwater natives.
However, if you'd like to keep a sturgeon in with a large cat, Stugeon and Channel Cats get along well. And a sterlet with some albino channels is a cool mix.