Incorrect. The DC metro allows bikes of all kinds outside or rush hours but explicitly requires a bag if your folder is to be taken on the train during rush hour. It is true that the MARC doesn't require bags for folders, nor does the VRE.

I don't think so, for three reasons:

1. In English, I think it's usually the case that 'and' has higher operator precedence over 'or', though it's tenuous I admit.

2. The explicit discussion of luggage as justification makes it clear, to my mind anyway, that everything must be bagged but that they realized that some "folding" bikes are disassembled and others are folded.

3. #1 and #2 above notwithstanding, the ultimate arbiter of the rules is the station manager, not the rider. So you have to take the most pessimistic interpretation regardless. Which is: bag your bike.