Garcia's participation at the event is predicated on the theory that he flew back from the GD East Coast tour in the break between Oct 18 (Minneapolis) and Oct 23 (DC) to play this gig, and the one with Merl at the Matrix on 1970-10-19
It is certainly possible that the recordings that circulate with this date may be mislabeled. Some of this material also circulates on a JA tape called Bark Sessions, there listed as studio at Wally Heider's. And none other than Mr. Charlie Miller has stated this tape sounds studio. So like is that case with many old tapes, we may never know.