>Floating point matrix calculations are non-deterministic.

This is not inherent to floating-point math. That actual (true) claim in the article is that different hardware and different hardware configurations produce different results. But deterministic inference is possible, e.g. llama.cpp on CPU is deterministic by default.

Floating point math is entirely deterministic. For a given set of inputs, the same outputs come out, every time.

using which floating point standard? IEEE754 is totally deterministic