If you are trying to conjure a reason to properly dispel A-theory you do not need to look to an extravagant abstract argument. Instead, one may offer a simple counter argument from real life examples.
For example, the satellites we send into orbit must have specially synchronized clocks that run faster so that they run the same speed here on earth. Why is this? Well simply put, it’s relativity in action. The physics of relativity predict that when something has a reference frame of greater velocity than some other object’s reference frame time will move slower for this object. This becomes a problem for the A-theorist (especially the Priorian A-theorist) since past, present, and future are properties of objects. I could be watching a satellite move through the sky and I would be seeing a present-past object. It would contain the properties of being now-present and once-past at the same time. This contradiction, of the past-present object, is why those who understand relativity in physics love B-theory. It seems like understanding things as being before or after one another is the proper way to understand things rather than some metaphysically serious commitment to “past-ness” or “present-ness” or even “futurity” of objects.