Does Appearance of Age Render God a Deceiver?

Not necessarily. Assumptions of initial conditions influence conclusions.
If the assumptions are wrong, the conclusions can also be wrong.
All aging techniques depend on decay rates/ speed of light(for age of the universe) etc for empirical measurements. The age of the strata depends on these measurements and other assumptions connected to gradualism.
So, in such a case the actual age of the fossils wouldn’t be more than a few thousand years.

For YEC to be right on the science, uniformitarianism must be wrong.i.e things like the speed of light, decay rates etc must change with time and other factors.
I don’t agree with them that this is actually the case, but its possible.
And if it is so, there is no deception on the part of God. He did not promise to anyone that he will keep things like decay rates, or the speed of light constant. Nor can we constrain God with respect to inital conditions.

End of the day, the biggest problem for YEC is not geological strata or fossils. Its the speed of light.