You're definitely going with the evidence, but the evidence may be misleading. Remember, the name of Sirius Black is NEVER vindicated prior to his death -- remember that the Ministry blames Voldemort's actions on Black during OOTP. So the "Wanted" posters could work anytime prior to the end of OOTP. Also, Dumbledore is still alive, which places it before the end of HBP. Add in the Tri-wizard tournament, the Beauxbaton girls and Durmstrang boys we saw in the "Ellen" vid -- I think we've got this one safely nestled in the end of 3rd year, beginning of 4th year (end of POA, beginning of GOF) . Sure, there's no quidditch during GOF, but there's the Quidditch World Cup. I'm not saying that FJ will take us to the World Cup, but there are many options here that don't necessarily put the whole WWoHP in a certain time: quidditch practice, an un-written exhibition game, or even a Time-turner trick. The point is, they want a number of things with WWoHP: the characters (alive), the stories, and the best scenes for FJ and the other rides. My guess is that a technicality ("There's no quidditch during GOF!") won't stop them from putting a kick-butt quidditch sequence in FJ. However, major details ("Wait a minute, that character was killed by this point...") would be a bigger issue, one that would have been stopped by JKR in the planning phase.
Maybe I'm reading into it too much! But it's fun....