Indeed. The NRO - rumor has it - has been launching satellites to observe the earth in the infrared for years..

Since you are looking at a warm planet you will never get your camera down to 7 K nor do you need to as all sources are close by and bright compared to the astronomical targets for JWST. So the shielding issue is somewhat different. Having Earth, Moon and Sun in the same direction so you can block all of them with a single heat shield is actually one of the reasons why JWST is going to the L2 Lagrange point.

I really hope this is true, but there must still be something different, because there's been years of delay caused by the solar shade not deploying properly.

This is a good take, I like it, the US has deployed tons of spy satellites, and if they think the sail/shield+Mirrors will deploy well because they have used it in spy satellites before then I'll believe it