I think we can concretely see with Amtraks performance around the country that commercial rail ownership with transit authority subleasing is a failed model. Hell, even MARC itself is a testament - the Camden line is way less flexible and has worse reliability than the Penn line, and thats because they run on CSX track. The Frederick Line is exclusively commuter with no flexibility and that sucks too.

That being said, there is no reason you cannot have concurrent transit and freight track. You just need 3 or 4 rails rather than 1 or 2, and the rights of way for rail can fit 4 rail lines in the space of a 2 lane with a turning median road.

I am definitely for expanding commercial rail lines, but I think private ownership of them is and has always been a mistake. Amazon doesn't build highways just for their trucks to drive on. Infrastructure is a public good that should be publicly owned and improved. Its in the entire state, nay nations interests to make Baltimore harbor as productive a shipping destination as possible, but if that means new freight rail is to be built, let it be built by the state and have the trains tolled to use the line so that the people can own those tracks and use them for their optimal purpose, or in cases like with modern transit needs be able to expand them to include passenger rail.