The problem here is caused by the initial split of the “free software” term and community. A is entierly correct in that X is open source, but since it does not follow the four freedoms (to run for any purpose, to change the program, to redistribute copies, and to redistribute your modified copies) it is not free (as in freedom) software. Notice that none of the above explicity require access to the source code, but it is in practice a requirement to fulfill the freedom to make changes.
This is already one of the reasons that RMS himself opposes the open source term:
Why do people misunderstand it that way? Because that is the natural meaning of the words “open source.” But the concept for which the open source advocates sought another name was a variant of that of free software. [From Why Open Source Misses the Point of Free Software]
The problem here is caused by the initial split of the “free software” term and community. A is entierly correct in that X is open source, but since it does not follow the four freedoms (to run for any purpose, to change the program, to redistribute copies, and to redistribute your modified copies) it is not free (as in freedom) software. Notice that none of the above explicity require access to the source code, but it is in practice a requirement to fulfill the freedom to make changes.
This is already one of the reasons that RMS himself opposes the open source term: