You act all high-minded saying 'in the spirit of impartiality,' but really you just don't have your own opinion, do you?
Literal
Impartial spirit [with-で], etc [quotative-と] pretentious [but-けど], ultimately own opinion [object-を] having-not just [question-じゃないの].
不偏不党 is a four-character idiom meaning 'impartial/nonpartisan.' かっこつけている = 'putting on airs / acting cool.' 結局のところ = 'in the end / when it comes down to it.' ~だけじゃないの is a pointed accusation. Very colloquial and sharp.