Since they haven’t recovered her body & maybe don’t have video of her leaving/exiting GGB, they can’t be 100% certain that she jumped. They must feel close to certain though, which is why we’ve seen such a subdued search response.
Sometimes I agree with your theory, and other times my gut tells me that she ran away.
I haven't had any luck in MSM finding reference to a cell phone ping. Maybe it was in the comments on facebook? But the clothing description makes me think it was a camera placing her at Crissy Field that morning, and any reference to a cell phone ping was someone throwing out a suggestion and nobody refuting it.
IF it was a cell phone ping, if my understanding is correct, that's done most often through cell tower triangulation. Again, if my understanding is correct, sometimes it is very accurate (a matter of several feet), but sometimes it can be a quarter mile or more. The 101 freeway is well within that margin of error. The optimist in me is hoping that she was fed up with this point in her life, paid for a bus ticket in cash, and headed north. For those of you who think of beaches, Hollywood, and San Francisco when you think of California, Northern California can be totally different. Think marijuana farms, remote forests, mountains, and beaches, and counter-culture communes, with a little bit of "Deliverance" thrown in for good measure (no offense to any Northern Californians reading this!). Much of the populace wants to secede from California and form the independent state of Jefferson. From reading her writings, I could totally see Syd having a romantic view of the hippie, off-grid life. If she wanted to get away and not be found for a while, she could have a lot of luck up there.
I've been having some guilt as to all of these postings. To my knowledge, I was the first to post of her Reddit account here. I thought it would be helpful at the time but now I feel like I found her diary and distributed it to the world. Syd, or your family, if you're reading this, I'm very sorry. I hope that you are safe and take the time you need. Feel free to send me a message and I'll gladly take down all of this. I might even do it on my own here shortly.