I would offer a suggestion, cancel your travel plans and go to the meeting. The "moron" you think you are referring to is Chris Simcox, not Shannon McGauley. He runs MCDC which does exactly what you say, he collects money. NONE of which goes to The Minuteman Project or Texas Minutemen. The individual being invited to speak is Shannon McGauley of the Texas Minutemen. You can find out a bit more about Chris Simcox here
If you go to the meeting you can explain yourself face to face with Shannon.
Keyboard cowboys don't like face to face meetings.