There might not be much in the way of proof, but it's an interesting story. Tesla calls police, says Tripp has threatened to shoot up place. Police investigate, say "no threat". Tesla says, "Hey, hold a press conference about it anyway!", sheriff declines, says "Can I speak to the person who says he called in a threat?". Tesla declines to make any witnesses available (which, huh? How can a company 'decline' to make a witness available for a criminal threat), but sends out their own press release anyway.
No. For one, it wasn't described as an anonymous threat. Tesla reported to the police that they'd received a threat from Tripp. The police said "can we speak to the person who received it?", and Tesla said "Uh, no".
But then expected the police to hold press conference to talk about how Tripp is a violent, dangerous menace.