Am I missing something here - what is funny? Obviously a cast iron garden chair isn't an ideal mount but its hardly going to take off, is it!
And a fold up work / saw horse has been used by many, the world over, since the 70's introduction for this very purpose. Now funny / peculiar / strange was a guy at a swap meet that had his engine stand G clamped to a fold up deck chair - so lightweight it could have taken off!