Without googling I have no clue what that sentence means: "I wanted to derisk my resume by working somewhere with high signaling."

It means he wanted somewhere impressive on his resume so people trusted him more.

In my opinion, this is an example of using fancy words to explain something simple that not only hides the meaning, but is actually less precise. The use of de-risk just doesn't work in the context of a resume. It's not "risky" to have a less impressive resume. it's just less impressive.

Agreed. "I wanted to buff my resume."