0 K is like when there is 0 heat basically, while celsius isn’t. Imagine a unit for distance called “goob” where 0 goobs is 100 m and 1 goob is 115 m. In that case the goob unit would behave differently than a meter when you multiply and divide because 0 of the units don’t actually correspond to “nothing” in a physical sense. That’s exactly how the Celsius scale is, with zero being placed somewhere arbitrarily, not at a physical zero.
Trump wants to weaponise the FCC to go against social media companies who “ban free speech” or whatever, just like Elon complained about before buying Twitter, and like all other right wingers are so mad about. But if the FCC doesn’t have any authority to regulate ISPs, why should it have authority to regulate social media companies. Not that the courts seem to care about precedent anymore, but that’s the silver lining they are looking for.