The idea that binary payloads add risk is not correctly understood. 

First of all, you can transfer virtually any binary payload via regular text events. You just need to encode it in text first. There are multiple ways to do this, but in practice, if you are afraid of binary payloads, you should be afraid of regular text payloads as well. There is no difference between the two. Criminals can use text encoding to transfer their binaries in plain sight. Legally speaking, the relay operator is as liable with text as with binary payloads. Pretending that this is not the case is not good legal defense. 

And second, we already transfer many binary payloads. NIP-04 DMs are binary. Private zaps are binary. GiftWraps are binary. Private lists of people and bookmarks are binary. If binary itself was the issue for an operator, he/she shouldn't accept any of type of encryption, which will break significant usecases in Nostr, like private chats. 

So, binaries by themselves shouldn't be the source of any extra risk . 

The problem is more related to the software and hardware infrastructure each relay operator decides to run. I don't think there is going to be a silver bullet type of relay that solves it all and thus specialized operators will become more common as we move Nostr forward.