Come to think of it, this is a tactic that for once won't normally favor the dragons (at least at low CR) since they're smallish for the same CR.
I do think this will become a more and more troublesome technique as we move up in CR, however. The normal arena doesn't have this problem since each combatant at least gets a move to place themselves further within the arena.
While I applaud the wit of using the tactic first, I suggest a rule change to prevent it from taking away the fun of actually fighting in combat in the higher CRs. Either that, or we're all just going to have to adapt for it in choosing our champions for size or multiple legs or such.