Do you mean that it would only be circumstantial rather than direct evidence? I just wanted to make sure I was following you.

I think the weight of as evidence might depend on whether they are pictures he took, or items he poached from the SM accounts.
If he was watching any of them closely enough to take his own pictures of them, I think that would nicely support the stalking and targeted attack theory. Especially if the pictures were taken at odd times, and the subject was clearly unaware they were being photographed. Like at night when leaving work, or through a restaurant window, etc.