About the policy of "supporters only of the presumptive nominee" & accompanying "purge" of others

Full disclosure: I have been a DU member for over a decade, and well remember how bitter the primary election cycle of 07-08 was (as a staunch Obama supporter from the first months of his declared campaign). Of course, there were few if any supporters of Hillary Clinton that had any problem supporting Barack Obama on or off DU, as far as I could see. And indeed, the political climate was such that Democrats had much smoother sailing INTRINSICALLY as opposed to relying on how distasteful the GOP choices were.
This cycle, I supported the idea of Bernie Sanders running -- and running in the Democratic primary campaign rather than as a 3d party splinter candidate -- from before he even announced, and have backed him from day 1 with multiple (albeit modest) donations.
I plan to continue to support him all the way, and if Hillary is the nominee, then in that situation I plan to join Bernie, as he has promised, in supporting her. I also support every effort to get as many Democrats to defeat GOP candidates in both House and Senate races, and have already donated in a number of these to Democratic candidates.

But I am aware that MANY MANY Bernie supporters, both on DU as among others that I encounter on the web, say at least at this point that they have no intention of voting for Hillary ever. There are many who advocate for what I think would be the counterproductive approach -- one Bernie surely is too smart to indulge -- of splitting off and running an Independent candidacy for president or endorsing Jill Stein or something if he isn't nominated. One reason this is counterproductive FOR BERNIE'S OWN MOVEMENT GOALS (and those of supporters like myself) is that any further effort to mobilize the more progressive Democrats WITHIN (as well as mobilizing outside) the Democratic Party would be largely foreclosed; this would be especially true of efforts to reach out to those who are progressive leaning and who backed Hillary in the primary campaign.

At any rate, Bernie supporting the Democrats would apparently NOT be sufficient for a lot of "Bernie-or-busters". I would like to both try to win them over during the campaign (particularly if they are eligible to vote in 'swing' states) but if they are purged or silenced on DU, that won't be possible at least here. Some suggest just going to other venues (like Reich's FaceBook threads) but that is rarely if ever as good a forum for that kind of discussion as DU

I would like to open up debate about the 'purge' policy. At minimum, those who cannot (at any point from the Convention on) bring themselves to support the Party's nominee should at least have limited posting priveleges, if that can be cybernetically accomplished by DU) in certain fora or forum, where at least their political allies in the primary campaign who now support the nominee can debate with them. That would I think be more likely to further DU's goals. And if posting privileges are limited, the danger of somehow damaging the larger site can be obviated

Personally, even this goes against my very strong free speech principles, but it would be better than the status quo

DOES ANYONE out there think there is anything to broaching this discussion? Is it permissible?