These types of situations often result from people getting last-minute anxiety and thus finding excuses to cancel. It's quite common when meeting up with someone from online dating sites/apps.
Correct me if I'm wrong, but my understanding of this is that he got caught up with programming and wasn't in the mood that day?
While this could just be a one-off, your time and energy are valuable and should be spent on people that are going to respect the value of them.
On the flip side, he could genuinely have had been too anxious to be in the mood that day. Men aren't always in the mood for sex and he may have just wanted to wait for another time. The best thing to do is to talk to him and wait to see if this is a one-time occurrence or if a pattern is developing. Jumping to assumptions without proper communication will often harm and/or prematurely end things with someone.
Other than cancelling, what else has given you the impression that he is creating a wall? If you want him to tell you what he is thinking, the best thing to do is to communicate your feelings and start a conversation.
Do you get the impression that he has the same intentions? There is nothing wrong with wanting a purely sexual relationship/one-night-stand, but you have to make sure that everyone involved feels the same way.
While he may be wasting your time, the best thing to do here is to talk to him before moving on to someone else. Worst case you just move on to someone else anyways like you would have had you not tried to talk to him. You don't have anything to lose from a healthy, honest conversation.
. We live about 100 miles apart and his work keeps us from seeing each other as often as we’d like. I don’t know that what I experienced is the norm, however. 
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