Asking if all these super long pieces are one long song is not much different than asking "Is 'Dark Side of the Moon' one song?" they're all suites that segue into each other.
I will say The Whirlwind or SDoIT are closer to epic songs than TAU, or Neal's Sola Gratia, or TFK's Islands. Because TW and SDoIT act like epics, there's a beginning, a middle and and end, with sections in between that move the plot along, so to speak. With TAU, the middle sounds like the end (last song on Forevermore disc 1) and the 2nd disc just sounds like a 2nd disc of related songs. Neal's edit makes TAU sound a little closer to being one song, but it doesn't cut the mustard for me. I still haven't listened to the Ultimate Edition yet, but I can't imagine it will change my opinion. The Absolute Universe sounds like it wants to be one big song but it just comes off like a series of individual songs with connecting themes sprinkled in, which is great for the full album experience, but tough for me to call these recent efforts by Neal, Roine, and co. true epics or one song.