I don't doubt that some railroad security people especially the so called "rent a cops" do hassle fans. They've been over zealous in preventing people from watching trains and taking pictures at stations and along the tracks.
However sometimes they do have to be aggressive with fans and suicidal people who walk on tracks and venture into off limits areas.
Unfortunately, some people who look like innocent fans taking pictures may actually be potential terrorists or crooks checking out the security around railroad property so they have to be stopped and questioned.
The railroads lose millions of dollars every year when organized gangs stop trains in busy urban areas and break into freight cars to steal TVs stereos and other products so I doubt that they're ignoring the problem.
Once in awhile there are stories in the media about successful efforts to catch the gang members to do this but we probably don't hear about all the railroad police do to prevent crime.
I know the railroad and local police along the SMART line and UP in the Bay Area periodically break up the encampments near their tracks so I don't believe the railroads are intimidated by the ACLU