Working within all the parameters the OP defined, I see no problem with what he's doing.
As far as depriving someone else from a camping opportunity, life sometimes gets in the way and you have to cancel a trip (too late to free up the reservation). We had one of those last year and on Monday we found out a friend happened upon our empty site and used it (without noting who it was reserved for). So that one had a happy ending.
In daily life, I kinda did the comparable thing. Moved away from a home on a 4,500 sq ft lot where houses were spaced just 10-feet from each other to a 10,000 sq ft lot where each home has to be a minimum of 10-feet from the property line. And relevant to this thread, my single-level house blocks the view my neighbor had for over 20 years. If he had the cash, he could have bought my lot when it went up for sale and preserve his view and privacy.