Detecting design or intent in nature

[Chas]

Not at all the same. Electromagnetic Theory proves all photons travel at the the same speed in a vacuum.

It is the same. It is the same because all theory is ultimately grounded in and derived from observation. The equations which derive the speed of light are still based on observations of other un-derived constants.....which leaves you with disjointed sets. There is the set of all the points of space. In that set are disjointed subsets. The set of points where permeability of free space has been measured and the sets of points where the permeability of free space has not been measured. According to your logic measuring the permeability of free space doesn't tell us anything about the permeability of free space for points of space we have not measured. The same would be true of vacuum permittivity. The value of these two constants are not derived by any theory. They are assumed to be constant based on observation. Is all of science really a sham? It would seem so if we take your thinking to its logical conclusion.

Nope. The speed of light is a constant that is intrinsically tied to all of physics, e.g. Planck' constant, electrical charge, the mass of the electron.
All of that is evidence for the speed of light being a constant. You have no such evidence for your contention.

This is yet another poor example since this is not at all parallel to your argument. In fact, this is a counter to your own argument.

Pro tip: The term is "disjoint subset".