I'd fire somebody for browsing 4chan at work. Shitting dick nipples, lolicon, and the occasional piece of child pornography does not need to be moving over our network.
I think you're confused about how 4chan works (except maybe /b/). And fortunately I live in a country where I can't legally be fired because my boss has personal grievances about particular websites
There's more than enough posted to /g/ I wouldn't want on a work PC. At this very moment there's a bikini model, a spread-legged underage anime catgirl, a Terry Davis thread, some furry art, more anime girls, more anime girls, an upskirt shot of a loli, some AI art titties, and the ever-tasteful "chink shit general".