MyDocs would be indeed stupid, as this one gets unmounted when you connect N900 to computer as mass memory, but I don't agree that it should be in /lib/modules instead of opt. Many people are not using them and they are >500kb and, as not essential for running kernel with working wifi, I agree with maintainer's decision to place them in /opt. See official packaging guidelines - these modules are now part of kernel power, but I somehow feel it's wrong to place these 500kb in rootfs (and let's not forget they started as a separate package, this is only first stage of their inclusion in official kernel power packages).

I still believe they could be symlinked, not placed in /lib/modules/proper-kernel-version/packet-injection-modules , but that's just my oppinion based on stuff I wrote earlier in this post.