NO WHERE in the article does it state that it was "just a hoax".
What the article said is:
"Sheriff's Capt. Dan Terry (of the Contra Costa Sheriff's Department) confirmed the possible early sighting of Dugard after being asked about it Monday by The Chronicle.
Terry said such tips are common in criminal cases that are highly publicized, as Dugard's kidnapping was in the early 1990s. He said his agency had responded appropriately, sending a deputy to the gas station, but that the yellow van was gone, as was the caller - who did not leave his name and has never come forward.
"We don't know if there was any truth to it," said Terry, who is head of investigations for his agency. "We don't know if it was real or a hoax. Nothing ever came of it."
Terry said the call was made about 6 p.m. on April 22, 1992, almost a year after Dugard was abducted on June 10, 1991, while she waited alone on a South Lake Tahoe street for a school bus. She was 11 when she was kidnapped and is now 29.
Police had no license plate to track and no good location to stake out, Terry said, and the caller did not say which direction the van had driven. He said dispatchers would have alerted other officers to be on the lookout for the van, and that a copy of the report had been sent to investigators in El Dorado County, who were leading the search for Dugard."
Maybe the original caller, if he is still alive and sees or hears about this news article, will come forward. In the meantime, I guess we can only speculate.
Personally, I speculate that it was a legitimate sighting and should be included in the timeline.