But the OP is not saying that people did not get power increases with the new traits. He's talking about guilds that were only able to make it to Gul'Dan thanks to the power increase they got from the new traits. It's not a debate that the new traits were a way of nerfing the bosses so the less skilled guilds could access the content. If they are allowing people to get the FoS for another week, it makes sense that it doesn't become harder for any guilds currently progressing on it. The guilds that are currently progressing on it are guilds that could not have done so without the power increases that they got with 7.2.
Yes, the fight is significantly easier with new traits, but that doesn't take away from the point that if Blizzard is allowing guilds to get the FoS for another week that it shouldn't be harder for those guilds that were only able to meet the DPS cutoffs with the boost in 7.2.
As someone else pointed out, guilds come in a full spectrum. Slight changes to the player or boss power level may only shift the cutoff for being able to kill the boss slightly in one direction, but that still means there are few guilds who suffer because of that. It should never be the case that the boss becomes even slightly more difficult to kill as long as the FoS remains and Blizzards seems to agree with that.