No, its more that Arlo doesn't believe John to be worthy of being king. If he exposed John, it would do nothing but cause chaos. I don't think Arlo really sees John as being more powerful, but in fact weaker and pathetic.
Not supported by what has been said in the story, at all. If Arlo wanted him to take some of the burden off of him (as was directly stated in one of the episodes itself) then he can't plausibly believe that he's ALSO weaker and more pathetic than he is at the same time now can he? Besides, Arlo isn't worthy of being King if he thinks that his selfish ass is more deserving of sharing the burden than John's was when he was King. It's precisely BECAUSE of people like Arlo that John was lonely at the top in his position as King AND at the bottom, after all. Kt.
In the end, if Arlo was really concerned about maintaining 'order' and 'hierarchy', he'd just expose John, then let John dethrone him as king since John's the more powerful one between the two anyways.
Instead, Arlo is just insecure and resentful about not being the strongest, or even the second strongest, anymore-- and more than that, in his mind he's always been THE rightful leader, and now that someone more powerful has shown up, he doesn't know how to adjust his world view to accommodate the idea of people stronger than him--- and him being obligated to do what they say.