Because we have such a strong two way hand, we're ok if they jam with J9 on the turn. I address why it's ok to size up here and keep our range more polarized. When I'm building a strategy it's based off my entire range, not what they will do on the turn with theirs. So if I get jammed on, I won't be worried as I have enough strong hands that I'm betting turn with that can happily call. As far as choosing a smaller sizing on turn, you could create a strategy that does that here, but in a 3 way pot I feel the better option is to use a bigger sizing.