Overall, I am sure that is correct. But there are some services that allow you to carry on/off you bike at any stop. The Keystone service between New York City and Harrisburg, PA is one example. The Vermonter, between D.C. and St. Albans, VT, is another. (I have taken that one from Philly to Brattleboro once and St. Albans twice.) I am pretty sure the Capitol Limited is also in that category. (Amtrak added a special bike area to cater to the demand from people riding the GAP and/or C&O.