I'm sure he would have been but you gotta respect that maybe he wasn't in it to become super rich ( I'm sure he is rich but he was fine with what he had).
Here's a quote from him merchandising:
Actually, I wasn't against all merchandising when I started the strip, but each product I considered seemed to violate the spirit of the strip, contradict its message, and take me away from the work I loved. If my syndicate had let it go at that, the decision would have taken maybe 30 seconds of my life.
Another on animation:
If you look at the old cartoons by Tex Avery and Chuck Jones, you'll see that there are a lot of things single drawings just can't do. Animators can get away with incredible distortion and exaggeration ... because the animator can control the length of time you see something. The bizarre exaggeration barely has time to register, and the viewer doesn't ponder the incredible license he's witnessed. In a comic strip, you just show the highlights of action—you can't show the buildup and release ... or at least not without slowing down the pace of everything to the point where it's like looking at individual frames of a movie, in which case you've probably lost the effect you were trying to achieve. In a comic strip, you can suggest motion and time, but it's very crude compared to what an animator can do. I have a real awe for good animation.
If I remember right he also had a hard time imagining Calvin's voices, and felt uncomfartbale about any of his characters having voices.