It's likely he didn't turn it in the correct direction or he used an impact on a bolt that was already over-torqued. As that shaft is part of the crankshaft and must have that retainer bolt for the clutch, if it can not be extracted the crank will have to be replaced...and by not drilling the center for an extractor/ease-out, he even lessened his chances for success. Still, if he hasn't drilled through any threads or peened it in any way there is a chance with some heat to the shaft and a left-handed threaded ease-out. It really needs to go to someone that knows what they are doing..like a machine shop or certified mechanic. Be sure the shop/mechanic knows it's a left-handed thread bolt. Otherwise, this is going to be a very expensive lesson on his behalf.