Heterocentricity: Hetero-, opposite; Centric, central.
I would interpret the term as being the concept that heteronormative ideals (two sexes, therefore two genders, each with their own set of expectations, ie. born with a penis, therefore male, become a man, marry a woman) is central (or most important) in the analysis of social, political, economic (etc., etc.) structures. That is, all things are explained from the viewpoint of someone who does not accept that there may be explanations outside the heteronormative perspective. Most often, one would see it in the context of, "I am heterosexual/cisgender, so I am 'normal'; and you are homosexual/transgender, so you are not!"
Heterocentricity is the assumption or belief that heterosexuality is the norm or superior to other sexual orientations. It can result in the marginalization or erasure of non-heterosexual identities and relationships in society. Addressing heterocentricity involves recognizing and valuing diverse sexual orientations.