I get where you are coming from. If it ever comes to a situation where you are forced to excert your authority, things could become awkward, also if it ever gets discovered by your flatmate on his own. Though your reasoning is easily understandable, so I'd say do whatever you're feeling more comfortable with but be prepared for getting found out.
Somehow I'm completely sleeping on that entire issue. I've been running JS-blockers, ad-blockers and privacy-protectors for so long, the ad spam went entirely by me. Every now and then I'm testing something on my add-on free, unmodified Edge just to see if it's my addons or the site is actually broken, and I'm shocked at how sites actually look compared to my experience. I wouldn't know how anyone is able to rawdog the internet.
The thing people who disagree with should die: "Maybe let's not be literal genociding facists."
I actually unironically do so. Nothing better for the world than that terrorist shithole collapsing into a civil war.
CorpoNations.