> Does anybody else find this kind of response patronizing?
No. "compassionate" is the description I would use.
> The parent said nothing about being in pain.
They repeatedly used the word "suffering".
> The parent posted a completely rational statement.
Not really, no.
> Here someone comes along trying to sound as though there is some moral or intellectual superiority to the opposite action
There is.
> and that this person needs help of some kind.
They do.
> Perhaps we would have more humane suicide options if society were to stop regarding suicide as some kind of dysfunctional behavior.
But in the majority of cases, it is a dysfunctional behavior.
> There are plenty of rational reasons to commit suicide,
Very few, really.
> and there are plenty of cases where not committing suicide seems rather irrational.
The absolute number may be large, but a tiny fraction of the number of people who consider suicide for irrational reasons.