It's also "physically impossible" for someone to gain access to a well configured IPSec endpoint, yet we still consider this a point of access that needs appropriate controls and security oversight. There are many, many ways that people collect key material to use to access tunnels to corporate networks. No matter how confident you might be in the technology, you should never provide an access point to a private network without full consideration of the security and compliance implications.
Perhaps the bigger issue though is that Tor at least used to be frequently used by botnets for C2, I'm not in a SOC environment any more so I'm not sure how much that trend has changed. But it's very common for corporate security programs to configure IDS to report on Tor traffic since it's associated with some sort of compromise a good percentage of the time. This does mean you get occasional false positives from normal Tor use to e.g. anonymously access public materials but that's life in a SOC. The point though is that most corporate environments ought to notice this kind of thing happening whether or not it's done with the approval of IT/security.