Do any companies develop machine specific port covers? I've tried searching but couldn't find anything.
You'd think for a Mac Mini for example that it'd be relatively easy for a company to produce a custom panel that fits over the Mac Mini's ports and prevents standard cables from being removed; this would also be handy for preventing cables from being pulled out accidentally (or maliciously). Then all you need are some dummy connectors, the locking plate keeps them in, making it impossible for someone to add a new USB device without removing the plate.
I'd love to get something like that just to ensure I can't accidentally tug a cable; while I'm generally very careful with my cable management to try to avoid this, it isn't as good as actual panel could be.
Anyway, more on target; I think this a bit blown out of proportion, okay so yeah, you could be vulnerable if someone unknowingly connects a USB stick or whatever with infected firmware into your machine, but surely the virus would need to have the right firmware for every device that it could potentially infect? That would be a huge amount of work, and if it broke the device then users would notice, so it'd have to be a seamless change.
Also, it's always been the case that if someone has physical access to your machine, then you're vulnerable; a USB stick with a bootable partition could let them install a malicious boot loader to steal your Filevault password, or change a user account's password to enable access etc.