https://wiki.sipeed.com/hardware/en/lichee/RV_Nano/1_intro.h...
I assume they didn't intend to put a mic on the KVM product, but they wanted to make a KVM product, already had this SBC product, which reusing their existing stock of helped keep cost low.
Should they have been more up front about it it? Sure, and it's not great that they had a bunch of security issues in the FW anyway, so not exactly great, but "hidden microphone in a Chinese KVM" lets the mind wander
Far more of an issue would be any kind of keylogger built into the software, which is why it's best to go for devices that support open source software.
But that doesn’t mean you can’t make it function in a loud server room. The whole point of it is working in and around noise.