this seems like a good idea, but the problem is that said preliminary judgment will influence all later discussions.I totally agree with you, but we can at least make preliminary judgement regarding the matter and see how it stands over time.
if people start saying "well we should ban arowana because of reasons x y z" then the discussion will always be about those reasons and people will only ever discuss those reasons. eventually this will have to happen, but the reasons should be the right ones and not just "well I saw a sniper go 10-0 on arowana once"
what needs to happen is people need to figure the game out some more, the weapon metagame needs to settle (which it won't for a while just because of the new weapons coming out), and more tournaments with randomised map pools need to be run. until we actually have hundreds of tournament games played between top level teams, we cannot begin the discussion. it's like quantum physics; the more you measure one aspect of a thing, the less certain you are about everything else.