In my experience of ABS it gives very rapid pulses and not the languid pulses you describe, but I don't know if the system can malfunction to give that effect? I doubt it.
If it were mine I would now be farging up a bracket to mount a dial gauge on the forks and then trying to find a hole free path round the rotor for the probe to run on.
Chances are that if the Italian tune up didn't glazebust the discs, then they are actually warped.. Sorry!
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