would have custom firmware designed to prevent intrusions like that

In-universe that's what ICE is referring to - Intrusion Countermeasures Electionics

None of my cyberware would even have wireless capability; I'd do all of my updates using physical media.

Realistically how many people use electronics today with zero wireless capability and do only updates with physical media? A tiny minority of highly security conscious people, the vast majority of us use wireless smartphones and an increasing number of IoT smart devices, because the convenience.