Is it permissible to stay in an internet cafe where some patrons access pornographic websites, knowing that the person sitting there uses the internet to seek knowledge from Islamic websites?

A man must denounce teenagers watching lewd websites. If he is unable to do so, he is not permitted to sit with them while they are witnessing such abominations, based on the Almighty's saying: "And He has already revealed to you in the Book that when you hear the verses of Allah being denied and ridiculed, do not sit with them until they engage in another conversation. Indeed, you would then be like them." This indicates the obligation to avoid those who commit sins when evil becomes manifest. Whoever sits in a gathering where sin is committed and does not denounce them is a partner in their sin. If he cannot denounce it, he must leave the gathering. This is the view held by most scholars, while some believe that sitting is permissible if one does not see or hear the evil.