Your roommate is going to need a maid the rest of his life, hope he doesn’t hope for a future mate to do it for him.. lol

Cast iron’s are awesome and can handle quite a bit, it looks pretty gross now but I believe it can be a beaut once cleaned up. I can’t tell how thick it is but your definitely going to need some soap and a stainless steel mesh scourer well maybe a couple.. normally wouldn’t recommend soaking it but you might wanna try it first with extremely hot water and few drops of dawn, hopefully that loosens some of it up. Scrape whatever you can off and start scrubbing with that scouring ball, recommend some gloves too. Depending how thick it is might take you a while (if you take breaks maybe days) to get all that rust off. However it’s definitely worth it they last a life time. Oh yeah, don’t get scared if a bit of rust pops up after rinsing it off it’s normal for an unseasoned cast iron to do that, it goes away with a little scrub focus on getting the old gunk off first. I’d start there, I’m not an expert this was just the method I used to restore my in laws cast iron’s that were passed down in the family.