Actually, we are in agreement, in theory. Russia no more belongs in Syria than the US belongs in Iraq.
The other side to that coin is this: Will the interference do more good, or more harm? That question cannot be ignored! But neither can it be used as an excuse for armed intervention everywhere, all the time.
I agree -- Putin has no excuse for armed intervention everywhere, all the time. Naturally, there are always plenty of his supporters online, giving excuses for everything he does.