I dont think that its that simple and you would also have to mention how strong the wind was during Omoregie's run.
In 2011 it took 13.56s (-1.6m/s) to reach the final, at 2012 olympics it took 13.31s (-0.5m/s) to reach the final
In 2007 it took 13.35s (-0.3m/s) to reach the final, at 2008 olympics it took 13.43s (-0.4m/s) to reach the final
In 2003 it took 13.55s (+0.4m/s) to reach the final, at 2004 olympics it took 13.34s (0.0m/s) to reach the final
In 1999 it took 13.47s (0.0m/s) to reach the final, at 2000 olympics it took 13.39s (+0.4m/s) to reach the final
In general we see very often that events in swimming/athletics get (much) faster in olympic years and i think we will see it again this year.
I think McLeod, Ortega, Allen, Parchment, Bascou and Martinot-Lagarde are safe to be faster than 13.25s in Rio and i am pretty sure that at least 2 out of Ash/Porter/Belocian/Xie will also be faster than 13.25s.
To sum it up: I think that 13.25s with a slight headwind might be enough to make the final in Rio, but i doubt that Omoregie wouldve been able to run that time under these conditions.
Edit: Apparently he had a tailwind of 1.2m/s and the race took place in Loughborough, a track that is known to produce fast times. At the same meet Joel Fearon (never heard of him before) ran a huge lifetime best of 10.04s (+1.7m/s). Omoregie only finished 4th at the british Championships with a time of 13.67s (-1.3m/s), 0.36s behind Pozzi ...
Do you have any explanation why he should be in a much better shape now?