If the phrase was "1.6x speedup" then I would agree and not have commented. But the phrase is "1.6x faster", which is a bit ambiguous.

That there is disagreement among the commentariat both ways is indicative of ambiguity. (Though, I am assuming no trolling here.)

While not exactly analogous, try replacing it with a percentage and re-evaluate: What does "60% faster" mean and what does "160% faster" mean?

They did say "1.6x faster", not using the term "speedup" (which is terrible nomenclature too, but that's not the point).

To say that something that's no faster is identical to something that's "1x faster" is a terrible confusion of thought.

It's reasonable to expect that, for example, "1x faster" would mean "for a baseline of 1 operation per second, it's faster by 1 operation per second, i.e. a total of 2 operations per second."

EDIT: Oh god, that's even before I saw the "1.2x slower" entries…

I agree based on my experience reading these types of comparisons. I've never thought there was any ambiguity to saying "1.6 times faster." It means performance_1 = performance_0 * 1.6.