> he was able to hide his addiction under a veil of eccentricity and a pyramid of residents
Which means "created an environment to allow himself to be high at work" to me. It's not impossible that he held it off at home, but I don't see why he would.
Also, he's clearly Dr. House; Ctrl-F "Leaving much"
https://pmc.ncbi.nlm.nih.gov/articles/PMC7828946/