A slight typo I made in the first post... it would use t-bolt clamps, not hose clamps (still same concept though). We used a similar method of attaching an arm on our
2007 robot and had no slipping problems due to chain tension. It is worth noting that that was an aluminum/aluminum interface, not a steel/aluminum interface, so the coefficient of friction will be less for this design. I don't think it will be slipping due to chain tension, though. (maybe from torsional loads from a robot pushing sideways on our arm, but that makes the slipping a design feature to prevent broken parts.
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As for the bolt attachment, all of twisting moment is being accounted for by the 2" steel tube. I expect the only force you will see on the indexing bolt will be shear stress, and the sprocket won't see any bending moments either.