I thought the Colonel (Walter Brennan) was a . . .

Maybe he's a prick, but his character is also offering sensible advice, and he acts consistently with his belief that freedom means little attachment and little pride. It's a fact that Coop is getting used, it only later becomes clear that this prank will amount to anything good at all, and at any rate, the Colonel has known him a long time and knows that whatever is happening to his friend is quite out of character. (To this extent there's a bit more complexity than you admit -- the Colonel says be unattached, but his friendship is challenging his ideals as he realizes that he does have cares in the world after all. It's not merely that he wants to fish, but that he's practicing his own version of tough love). But sure, the message of the movie is that love of humanity is the highest good, and so the Colonel's little ideology about "helots" is being set up as something of a straw man.

Actually, I have thought his character might be a pastiche on the Calvin Coolidge - Herbert Hoover political philosophy; he's a good man but irrelevant to the social problems of his time. The publisher is sort of a Hearst, making some of the right noises but not to be trusted with too much power. The "true John Doe" movement is a variant of Christian (especially Catholic, although none of the major protagonists really appears to be coded as a Catholic) anarcho-socialism that is ultimately portrayed as the only way to avoid the hard-heartedness of the Coolidges and the potential demagoguery of the Hearsts). In between, the reporter and the faux John Doe are FDR and his allies: they are both sort of opportunistic (she shifty, he desperate) but they develop real values when they see that they have been the catalysts of something much bigger than themselves.

None of these characters maps perfectly to a real individual -- the movie is politically very cautious -- but what is interesting is that the film does sort of draw together all these poles of Great Depression opinion and try to teach them all a lesson about transcendant values.

I think it fails, but that's another story.

He had his faults, but all in all he was a nice guy. And how dare you call him such names, you heelot!

I didn't think the Colonel was that bad. He did see that John was being used, but then again John knew that too. But John needed the money to get his arm repaired (Tommy John surgery?) so he could pitch again. The Colonel if anything was too cynical of the world being "helots", and though he had a point, he really wouldn't look at the good points of making a good living, and later of what the "movement" was doing.

But the Colonel was right in that what John was doing would lead to trouble (which it in fact did in John almost jumping off a building). But the Colonel could have been more supportive of John, especially when the soda jerk was telling John about the movement, instead of running away and leaving John to the wolves.