Never even knew it existed until you mentioned it. It looks like a ripoff of the Czech "Scorpion". Maybe Afarat chose it because he couldn't handle a "manly man" cartridge like a 9mm.
Another interesting choice was Hermann Goering's S&W Model 10. He could have had his choice of any pimped-up Walther he wanted (sorta like Saddam and his buddies, but with exquisite engraving rather than cheap gold plating), but instead bought on off-the-shelf American cop revolver from a gun dealer in Hamburg.
CZ61 is much smaller that the PM 63 ......yet has same design features as you point out. I was in Italy when the Brigatta Rosa aka Red Brigades killed PM Aldo Moro with a CZ61......