I think Rumble is an even more extreme case. The guy was way bigger than Till and somehow managed to make 170 at one time. He also had way more weight issues than Till.
I'm quite interested to see if Till can make weight for this upcoming fight. I think he's filled into his frame so much as of late, I doubt he can make 170 now. The guy looks to weigh like 210. Even if he manages to slim down to 200, cutting 30 pounds to make 170 is tough. That's 15% of your bodyweight, which is nearly the max you can do without risking hospitalization.