The forestry person normally should it know better. ML hunting was never forbidden by law in GE. It was not well seen from some members of the hunting association in GE. The german hunting law rules only that hunting with bows and crossbows is forbidden, but not with ML. The ML have not even bring the 100m energies which are ruled for riflecartridges (1000 and 2000 J at 100 meters). Because as the law said it is only for rifle cartridges and a ML don't shoot them. The energie rules are also not valid for shotguns when using slugs. But nevertheless a .54 with conical and a strong load is able to reach 2000 J at 100 meters, so you can use it for red deer, wild boars and other biggame. The minimum energy for roes is 1000 J at 100 m. This is even brouhgt by cal.45 with conicals. But as I said a conical isn't necessary. You can also hunt with PRB's. If your friend can't believe this, he can ask me.
Some of the modern hunters in GE have problems with the ML, because you have no big scope on it and that needs a good trained shooter. Many GE hunters are embarrassing not well trained in rifle handling and shooting.
Greetings from Bavaria.