He was there when Owsley, the manufacturer of Clear Light Acid, parachuted in.
Anyway, it's false according to this article in the Rolling Stone. I was there and don't remember anything like that happening. That article says that Owsley gave away 300,000 tabs of acid there and that seems to me to be an exageration. Elsewhere I read 10,000 and that surely would have sufficed.
The other errata is that keen-eyed Victor Sergeyev noted on the Zen Mind, Beginner's Mind page on cuke that I'd written that the 40th Anniversary Edited of with my afterword was 2011. He pointed out it was 2010, November to be exact. Victor was involved with the Russian translation of ZMBM and noted errata in it that no one else had for all these decades. Here's a page for his remarks in the ZMBM section on cuke. - dc