I just went to Oxford and it says:
play God: behave as if all-powerful or supremely important.
Notice you cite play god - now what does it say under God or do you want to shift the goal posts again?
How is the goal post being shifted? He chose the Oxford dictionary. If I choose another dictionary are you going to say I shifted the goal post, because I didn't use the dictionary you wanted me to? That tactic is not going to work with me.

The term references god as being all-powerful; therefore, my argument is valid.
The term god as described by the Yahoo! dictionary:
A being conceived as the perfect, omnipotent, omniscient originator and ruler of the universe, the principal object of faith and worship in monotheistic religions.
So, now what? Do we find every dictionary on the planet and tally up which ones refer to god as all-powerful and which do not, then make a comparison?