Spiner himself explained,
One of the ideas that John Logan and I had about what the next film would have been was a Justice League of Star Trek. Something would bring all the great Star Trek villains together, from Khan to Shinzon, and Picard is the only person who could stop them and he actually has to go through time and pluck out the people he needs to help him. He goes back to the moment before Data blows up and takes him back to get Kirk and Spock, and go even further back and get Scott Bakula’s character, Archer.
I can’t imagine it would have been good, but boy do I wish I existed in a universe where this movie had been made.
God, this pitch makes so little sense on so many levels. Star Trek has never been about the villains, so having a batman-style villain team-up makes no sense. Seven samurai in space with time travel is a reasonable pitch, but why would you need to build a team that involves a captain, a captain, a science officer, and a captain?
Same reason we got a whole season pulling the old TNG crew back together, I guess