Spoofers, hackers, cheaters, no matters what Niantic do, they will always exist.
I agree on most you said but for me trading, as pvp, it has to be released as soon as posible, we, the legal players, deserve that feature, just because there are hackers and cheaters there is no excuse to stop bringing features into the game. Spoofers benefit from free coins, from high iv/cp mon, from a complete dex with all region exclusives, from all stops they want, dust, mons...If they also benefit from everything that is currently in the game what could be worse? They already can have EVERYTHING, trading and pvp will only bring more action and fun to us, not to them.
So for me they should implement trading and pvp for sure, just make it a phone to phone close action, for example you have to be within 100/200m away from each other to actually trade or battle. I believe they will do it do this way, someone at Niantic said it in an interview and I think it is a good idea.