I suspect that they want to make sure nothing heavy is on it and nothing can easily fall off of it if they hang the bike from hooks. Thus, empty harnesses and frame bags that are small but attached with lots of straps might be deemed ok by individual Amtrak employees. I would expect that pumps that are strapped on are ok, but frame fit pumps that only are held in from spring pressure might not be.

But I have seen that different Amtrak employees have very different opinions on what the rules really are and what the rules mean. I had one Amtrak employee tell me that I was violating a luggage rule, I told him to look at their website and check the rules because I was in compliance. He then told me that since it was less than 45 minutes before train time, he could prevent me from bringing my luggage on board. I then reminded him that I had been waiting for him to sell me a bike box for over an hour already and that he said he could not help me an hour earlier because he said that he had to go to make a phone call. He was the only Amtrak staff person at this station, so I could not get help from others. I and my luggage got on the train, but the lesson here is that what works at one station and one employee might not work elsewhere. He cited some other rules that I knew were false, but I let them pass.