You would just have to debunk this crackpot. For details see here
Problem is, he's really nuts , so proving him wrong appears to be a real challenge.
Will he pay? No, but should be fun to see what he'll do.

Here's my quick explanation using a very simple analogy...wonder if it will do, Pupamancur?

The velocity-dependent time dilation factor in the theory of relativity is akin to the doppler shift of sound waves. Take two speakers that both emit a tone of the same frequency ( = sync the "clocks" ). Now put both on two cars, have the cars head towards each other at some speed (it doesn't matter what speed, just have it below the speed of sound). Both cars will observe the frequency of the other speaker to be different. Now...suppose we had a clock that marked its ticks by the frequency of the sound coming from the speaker. The two clocks on each car would each read the other one as being faster! Is this a paradox? No, not at all...it's just the wavefronts coming at you quicker.

The time dilation due to relative velocity in the theory of relativity is just like the doppler shift, except that because it is in 4-dimensions, we always observe it as being slower no matter the sign of the velocity. The regular doppler shift then occurs on top of this time-dilation 4-dimensional doppler shift.

So, what do you think?

That's an interesting one Pupamancur.

I reckon I've got spacetime down to a T, and while I have a "velocity is king" slant I've never seen SR as wrong. But I notice he says the time unit does NOT need to be defined so I'm interested.

Hey. Thanks.

twin paradox is not a paradox at all
speed of material change is slower in faster inertial system
but both systems moves in a-temporal space