That was my initial thought as well: this would just become an arms race to submit your trade last? But maybe if the trades were priority queued it would negate that.
How does a priority queue work?
If the trades are priority queued, then you have just recreated the speed "arms race" that this idea hopes to eliminate.
Maybe it cancels out the advantage of being ‘first’? I am admittedly well outside my area of expertise.