Hmmm, even if it may be a bit simplistic, do you really think there is not some truth to it?
Simplistic and disingenuous. It is an attempt at distraction by those who wish to divert attention from punishing the most horrendous breach of international law in recent history.
It is rather like arguing that Op Desert Fox (which, in terms of scale and planned effect, is probably the best recent comparison to what is proposed here) had the object, above all else, of helping radical Islamists.
Of course al-Qaeda (just one of an array of armed opposition groups operating in Syria) may benefit from a weakening of Assad's forces, but that is not the object here. Indeed, it makes it even more important that any military campaign should be calibrated so that it punishes the regime without precipitating its immediate downfall.
Of course there are uncertainties, but if you cannot stomach uncertainties, then why bother having Armed Forces at all?