When a being that does not belong in the universe in which Equestria exists in lands there, they usual do one of several things. They either:
A) Start screwing things up just by being there.
B) Use knowledge of future events to screw things up/change the future
C) Become the 'white knight' of Equestria.
D) Become romantically involved with one of the inhabitants. and do little to nothing.
Or E) Do nothing and just live a relatively normal life.

For Jake Linfield, an Orbital Drop Shock Trooper who crash-landed in Equestria after the portal transporting The Pillar of Autumn suddenly closed and sent him there via wormhole, he choose T) Start a taco shop. What could possibly go wrong?