Rubbish, unless you can back it up.
The concept of diplomatic immunity has no connection here, and frankly, it's absurd.
An Iraninan diplomat in the Iran consulate in Syria has diplomatic immunity from *Syria*.
A targeted assassination is not a legal procedure that needs to be done in a specific jurisdiction.
Iran declared war against Israel. They have no diplomatic relationship with Israel. Diplomatic immunity, by definition, can only exist between parties that have a diplomatic relationship.
The target was actively engaged in warfare against Israel. You don't have immunity to shoot at your enemy if you're doing it from your consulate.
And again, targeting someone in a consulate in Syria is not as egregious as targeting someone in Iran proper, and they've done that already numerous times.
This attack was not unprecedented, and this kind of talk is only because of the talking points that are trying to turn Israel into the aggressor or an "escalator".