I would normally take it with a grain of salt, but in the past, hasn't he been pretty good about making it clear it's not completely set in stone? The way he phrased this, it seems pretty firm. (assuming it's him making the facebook post, of course)
Yeah, that is when Red HOPES to have it out, don't take it as an official release date.
This time it IS an official release date. He even made a post on the TO forums saying it WILL be released on October 1st. In the past it was always just tweets saying "I'm aiming for x date" or "I'm hoping to release by x date".