Who on earth does that?  It's creeping me out.

Don’t give your exact location address until just before your appointment and no one needs the room number until just before arriving.  

By 5:30AM. I am talking about an outcall in DC at like 7:30AM. Early morning appt. if I am waking up earlier and putting in the time to get up, get ready and fight DC traffic to get to the outcall I want the room number the night before. And no one has ever denied me my request.  

You said "The ones that don't, are the ones that ended up disappearing on me" and then you said "Honestly everyone had been just fine when kindly asked."  Has everyone given you the room number the night before or have some people refused only to not answer when you arrived?

If I were the gentleman in that scenario, I would refuse.  Not so much because I'd have a problem with divulging, but because I'd object to being treated like I'm going to be an asshole.  While not outright hostile, it pushes the interaction into adversarial territory, and no one wants that.  Every companion wants to take precautions to ensure that their time isn't being wasted, but too many don't consider what tone they're setting with these demands.  

There were a few times the provider gave me room number in advance.  Thought it was a bit out of the ordinary, but everything worked out well.  

She wanted me to tell her my room number when I checked in, when our appointment was a day later. Had no problems. She didn't come to my hotel room unexpectedly, and even if she had, I was out of my room most of the time

Not a regular to DC. Just noticed this thread. See an earlier thread:
http://www.theeroticreview.com/discussion-boards/ter-general-12/no-gps-for-hotel-rooms-926483?frmSearch=1#926483  
Room number when?
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and this exact example on the NYC board:
http://www.theeroticreview.com/discussion-boards/new-york-2/can-we-wait-a-moment-please-257046?frmSearch=1#257046
Early morning NCNS up with a fake room number.
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As noted there:
Not everyone knows their room in advance, especially if a late check-in.  
Sometimes, rooms get changed, even late at night. (E.g., faulty temp control, couldn't sleep, asked for a new room; friend saw a rat (not a client, a small rodent) in her room (at a high end hotel!) and demanded a switch. (I think she was imagining things, but she switched rooms at 2 AM.)  
Nobody wants a stranger "staking out" their room, possibly hours in advance.  
You need the location (hotel, nearby intersection) enough in advance to plan travel (google maps) but you don't need the room until just before.
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YOUR situation would imply that he is checked in, you have contact late at night to confirm his arrival, and want the room number to make things easier the next morning. Not too unreasonable but I don't see a disaster if he chooses to wait until the next morning.  
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If you are afraid of crickets when you arrive without a room number, you can also get no response even when you arrive with a room number. Maybe it was a fake room number (across the hall - I've had a provider direct me the opposite room number across from hers or off by one floor).

I don't think that I would do it on the first date.  

The one that dissappear (VERY RARELY), want the appt and then when I tell them to give me the room number by 5-6AM, I don't hear back from them.  They are the ones that weren't serious. They aren't afraid of giving it out. I am not waking up early and leaving my house to go an early morning outcall without that info. This is how I have done it since I have started in this business.