Sounds like bad intentions gone worst
What is the problem of a girl eliminating a dude ? =P
Also, there are lots of chess tournments that allow everyone
There's two things going on in that story. The original page Reddit found was for a Finnish regional tournament that said it was male-only. The organizer of the Finnish tourney said they made it male-only because it's a qualifier for an international tournament run by the IeSF, and the IeSF set the male-only rule for its own tourney. The Finnish tourney then made its own male-only rule because they didn't want the potential case of declaring a female player a winner, but then have her unable to compete in the international tournament she qualified for just because she was a woman. FWIW the Finnish organization hosting the tournament says it's lobbied for equal gender representation in the IeSF, apparently to no avail so far.
tl;dr: Finnish tourney is male-only because the IeSF tourney it sends its winners to is also male-only, and the Finns don't want to declare a winner who is ineligible for the IeSF tourney. Still sucks, and the Finns could take a stand here, but at least more understandable. The IeSF can still go screw themselves, though; they can't pass the buck like the Finns did.
The article seems to indicate that there are female only tournaments? If so this isn't too bad.
There are, but a) there are fewer female-only events at the IeSF tournament, and b) each gender only has access to certain games. Women can't compete in a Hearthstone tournament, for example, despite there being absolutely no stated reason for blocking this. It's worth noting that athletic sports have similar issues from time to time, but in most cases there's at least a pretense given; women's ski jumping was barred from the Olympics until Sochi 2014 because the IOC said there weren't enough competitors and they were concentrated in too few countries to make it viable. Even this was controversial for a time (and came before Canadian courts when Vancouver held the games), and Sochi had women's ski jumping as a medal sport.