It's been many years since I lived in Baltimore (Charles Village), but I recently had to check on a few things on commuting. Depending on where you live in Roland Park, if you husband can walk down to the the Johns Hopkins University campus, they have a shuttle that runs from the Homewood campus down to the medical school campus and it stops at Penn Station. It used to be once an hour with a few extra during morning and evening commutes. The shuttle now seems to run all the time. It's like 15 minutes between shuttles for most of the day:
http://www.parking.jhu.edu/HomewoodJHMIOctober2012Schedule.pdf.
So, he can walk to Homewood, take the shuttle down to Penn Station, take the Marc from Penn Station to Union Station and the metro from Union Station to work. It's long but it's done by many people daily. And it beats driving hands down. Using this system, he can read the paper, work on a laptop, do work, read, etc on the train. Currently Marc does not have WiFi, but both Baltimore Penn and Union stations do. So if he works on email off-line, he can send them at both of those stops.