A few reasons I think it is not stupid:
1) Cuts costs. With the GWOT, Katrina, Iraq, and all our other problems I could care less if the USAF or Denmark doesn't get their F-35As. (no offense intended, Denmark
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2) I believe the F-35C is longer ranged than the A. Making it more useful as a bomb truck, which IS what the F-35 will be after the first day of the air campaign.
3) Perhaps the armed forces will do someting REAL novel. Like experimenting with true "joint" capabilities. Leave those arresting hooks on the USAF's F-35Cs...You know the AF will be tempted to try landing them on carriers. Yes, a pipedream I know. But it would save tons of money if someone followed through on the idea.
4) I hope that foreign customers will pull out of the program. I really do. I do not support "made for export" stealth technology. Even if Norway did pay for 1.67% of the R&D. (again, no offense intended Norwegians)
5) The USAF will not be loosing any capability. Yes, they may not get a gun. But frankly I think putting a gun on a $50-60 million dollar jet invites the pilot to take risks with the machine that aren't worth its loss.