Here's my understanding of your key disagreements:
1) You believe that some of the policies that Matt sees as politically toxic could be sold better to the public
2) You believe that arguing with people "to your left" is politically costly and therefore Matt is doing the movement a disservice
Whereas Matt believes in the "centrist" framework where fighting with people on the further end of your party makes you more favored among the general public
Comments
1) You believe that some of the policies that Matt sees as politically toxic could be sold better to the public
2) You believe that arguing with people "to your left" is politically costly and therefore Matt is doing the movement a disservice