I was just wondering the exact issue when this took place, revealing the Punisher was in the back room when Matt declared himself the new Kingpin.
Matt was suffering *another* nervous breakdown when he made himself the new Kingpin, more from his grief over Karen's death rather than the stress of his identity getting "revealed." The Punisher's crazy, but Daredevil *was* the one with "a screw loose" here.
In DAREDEVIL #92 or #93, Vanessa Fisk comments how selfish Matt Murdock is. With him going "It's mine! All mine!" here, I see why she thought this.