You're probably long gone as you only posted one thing on this forum over a year ago. I'll try to answer to the best of my knowledge if not for you, for anyone reading this who is curious.

Landing clearances being canceled are very rare. This usually occurs when a controller misjudges an airplanes approach speed, or attempts to get someone out in front of them and he doesn't move fast enough and ends up cutting them off. I'm guessing if you were really that close and he did that he ONLY did that to cover up for an airplane that pulled out in front of you and basically committed an infraction known as a runway incursion. Since it happened on his watch it sounds like he was covering his tail. If you are told you are cleared to land that is YOUR runway, unless you are told "cleared to land number X" where X is your number in line.

Remember, all pilots can simply say "unable" to any command given to them by ATC. Pilots don't realize ATC is a guidance to pilots, not a director. Remember, YOU are PIC of that plane, not ATC. Since its your tail that would be pulled out of the trees if you crash, its your tail that can tell ATC to stuff it if you don't like their last instruction.