I know it's not true, ZM, but it would appear to follow so from the logic of the OP, talking about 560,000 petitioners as if that is a small number. In context, it's a massive number -- the largest volume of signatures on any current petition on the government's e-petition website, and also of comparative size to those on the well-organised petition sites such as change.org or avaaz.
Petitions in general don't attract all that much attention. Most people, it seems, just don't care enough. So if a subject manages to attract the attention of the apathetic by so much that it's picked up over half-a-million signatures, that absolutely shouldn't be dismissed lightly as "only" -- and by citing examples of lower-volume petitions I was trying to make the point that AOG's likely using that qualifier mostly because he disagrees with the petition.
As it happens, I've not signed this petition and don't intend to. The government's vague response about "continuing to use available powers" is entirely appropriate in the circumstances, because it's a pretty stupid suggestion to try and ban Donald Trump from the UK, no matter how abhorrent I find the stuff that spews from his mouth.