What does "Selsick" mean in this sentence?

It is a person’s name.

Grammatically it is a name otherwise it couldn't enroll though.

It's definitely a name – the question might be referencing [the sleep scientist Hugh Selsick](https://www.thegrovepractice.com/profle/dr-hugh-selsick/).

It’s definitely a name— because of the context and the way the sentences are written.

Selsick is doing the action of enrolling, so the pronoun "he" that comes later in the sentence is referring back to Selsick. In English, gendered pronouns almost always refer to people or animals, so we can infer Selsick is a person or animal. Unless you're reading a fantasy book, the act of enrolling in something is a human action, so we determine Selsick is the name for a human

Selznick is a person’s name.

It’s the name of an actual real-life sleep scientist. https://www.uclh.nhs.uk/our-services/find-consultant/dr-hugh-selsick

It's a name.

Looks like a name.

A name

It's definitely a person's name. Not one I've ever heard of, but that's how it's being used here.