Trump would be perceived as “knuckling under” to the establishment if he signed their pledge. At least by some, subconsciously by many I think.
Not good for an anti-establishment candidate.
I think that may be the real idea behind this, after all.
No, I think they don’t want the party split which would ensure a DEM victory - and it would. Trump said he wouldn’t run 3rd party if they treat him well. However, he never outlined what that entailed. I don’t perceive it as knuckling under to the establishment. I see it as the establishment embracing him as a legitimate candidate. If he does sign it - then those who get their panties in a was over it have the wrong agenda. We want Trump to win, but, he can’t always be a lone wolf.