Bjarne whining about the word "ruler" just shows how ignorant of SR and GR he is determined to be.
For an observer, a ruler or clock is invariant. Their ruler always has the same length. Their click always ticks along at 1 second per second.
What SR and GR state is that measurements taken by that observer with their invariant ruler and clock of an object will change according to their velocity relative to the object and the relative gravitational fields. For example they can measure with their invariant ruler and clock that the objects length has contracted.
Another observer with their own invariant ruler and clock can look at the first observer and measure that the observers ruler and clock are length contracted and time dilated. This has no physical effect for the first observer on their ruler and clock - they are still invariant.