When the characters are revealed as being alive barely a few pages later, it hardly counts. The purpose was to have the other characters believe they were dead and then figure out that they weren't for plot purposes, not to trick the audience into thinking that half the main characters had just been unceremoniously killed off, no different than when the X-Men "died" in Dallas. Heck, by that logic, Byrne's Alpha Flight was full of shoddy writing between Sasquatch's fake-out death and those of Northstar/Aurora/Talisman when they went to go bring him back. It was just a story beat. You need to actually read the thing for yourself before you judge it.
My only real complaints against GLMK come from the way that, like I said before, it is really heavy-handed in places, which, considering the way Claremont normally gets when dealing with matters of race or religion, is really saying something, but the strength of the story pulls it through, IMO.