It's like your laptop's motherboard detected you installed another OS in place of the OEM-provided Windows installation, and overvoltaged your NVidia GPU to burn it out. "We have every right to not support high-performance graphics on any other OS other than our own - if you want to install your own OS, you can still use the integrated Intel GPU".
In other words: there's no way for me to just take the phone to my workshop / local hackerspace, and fix it with a soldering iron. Even if I could source the right parts, it's going to be a PITA to make them work. I didn't investigate it further, but I assume that these days, cryptography is used for critical parts to attest each other as genuine (similar to what new iPhones do, which is why you can't just replace the "home" button if it breaks).
Additionally, since I haven't heard of people doing software workarounds, whatever in Knox is reading the state of the eFuse, cannot be trivially patched. I recall reading somewhere that triggering the eFuse somehow overwrites Knox itself - if that's correct, then they may not even be anything left to enable afterwards.
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I'm going to concede here that my example was somewhat hyperbolic - burning a single eFuse isn't the same as overvolting the whole GPU. But only somewhat - the reasoning/intent behind the two cases is the same. Additionally, cryptography blurs the line between what's hardware damage and what's a software limitation. Take, for example, secure erasure of data: you can smash a hard drive with a sledgehammer and then microwave the remains to slag, but you can get the same result by keeping the data encrypted, and then... losing the keys.