You may have gotten the contact information from a public source, but using it with intent to harass or worse is still wrong and probably against some law. It's also a good way to get Altamont rather abruptly shut down, permanently.

You won't change his mind. So work rationally with the others in the system who actually make decisions, explaining calmly and with backup information where he is wrong or why it's not an argument against trains - it's an argument for supporting bicycles and other trail users which can be done while keeping and using the railroad. In legal terms, let him throw the first punch, not you.

Frankly, RTC has spent a lot of public money on the line under the guise of returning the railroad to service, and I'm sure expects to get some use out of it as a railroad line to compensate for that. They did not get rail money to build a bike trail, though a trail may eventually be in the corridor. The Brian issues are a sideshow unless and until he takes more formal action. Don't be the one provoking that action.