A lot of the polarization is due to various kinds of puppetry and wishful blog-pimping, I thinks. It doesn't really matter unless it gets out of hand and impacts FR unduly. At which point JR will engage the ban.
Apparently only conservatives care about birth citizenship, so Trump probably can exploit this (and FR!) without impact on the general election. Face it, the RINOs and the media will give Trump a free ride on Cruz birther attacks, and it probably doesn't matter to the general election. If the media play it, it will appear in FR.
Candidates must play an effective game to win the nomination. That's all that matters right now. Frankly the RINO elite is still in apparent control of the convention, so all candidates must flirt with them one way or another. For now.
The CRUZ Trump battle should be broken down to constitution original content or living document once paper work is filed. Most Cruz supporters
do not think of this aspect at this time.