I smile sweetly, praise the kindness of the person delivering the meal and just freeze whatever is brought into portions for DH to have unless it comes from someone I know is kosher.
I appreciate the thought and it means DH has meals for a bit longer while I get on my feet.
Also I find the ones that bring food that I can't trust tend to be people I don't know as well and therefore I don't feel comfortable telling them what they should and shouldn't be cooking iykwim. Plus I hate imposing my food restrictions on other people.