I wouldn't say it's trivially wrong but it's pretty much always wrong. There's two notable sampling parameters, `top-k` and `top-p`. When using an LLM for precise work rather than e.g. creative writing, one usually samples with the `top-p` parameter, and `top-k` is I think pretty much always used. And when sampling with either of these enabled, the set of possible tokens that the sampler chooses from (according to the current temperature) is much smaller than the set of all tokens, so most sequences are not in fact possible. It's only true that all sequences have a nonzero probability if you're sampling without either of these and with nonzero temperature.
In a given run, only the top-k sequences are selected.
Across all runs, any sequence can be generated, and potentially scored highly.
Thus, any sequence can eventually be selected.
There will be details like rounding errors that will make certain sequences unreachable in practice, but that shouldn't provide you any comfort unless you know your dangerous outputs fall into that space. But they absolutely don't; the sequences we're interested in - well structured tool calls that contain dangerous parameters but are otherwise indistinguishable from desirable tool calls - are actually pretty probable.
The probability that an ideal, continuous LLM would output a 0 for a particular token in it's distribution is itself 0. The probability that an LLM using real floating point math isn't terrifically higher than 0.
So it's only wrong in a technical and pedantic sense. A better phrasing might have been along the lines of "There are many sequences of tokens that will destroy your production database that are within the set of possible outputs"