Earlier quoted context omitted.
The offending tweet was arguing against all forms of suicide, assisted or otherwise. I'm trying to understand your point charitably, but it escapes me how arguing against suicide could be interpreted as arguing for suicide. I understand that there's a consequentialist argument ("it is going to happen anyway"), but that seems to accept something as inevitable which is not.
Going against legal abortion yields more illegal abortions. Going against legal alcohol yields more illegal alcohol. Going against legal X yields more illegal X. Same concept, going against legal suicide (euthanasia) yields more suicides. Sure overall the number of suicides might go down , maybe even very noticeable, but the quality of care would suffer tremendously. I'm not arguing on suicide vs suicide, but on the…
That argument is rationalization, and not material, regardless of which subject you substitute for X.