Usually being on the general university network is sufficient to get journal access. Using the university network credentials for the academic, it probably goes SciHub -> School -> Journal. So the school would have to block SciHub/discipline the academic. Disciplining people with tenure is hard, although maybe it is just graduate students giving the credentials idk.
There are many easy ways to get it to from others. Most students at Universities have access to the journal subscriptions as well. They get access by logging in with their University credentials OR using the barcode on their student card. BOTH of these are lost very often. People so often enter their details in a phishing site and lose their credentials, but what can also happen is that someone finds a lost student card and will take a picture of it and post it on Facebook asking if anyone can find x person.
This student card is typically on a public Facebook page and anyone could just use that code and get access to a wealth of journals.