Thanks for your response. I think we simply have different definitions of “equanimity”. The more I personally feel I develop it, the more I think back to a reading of Path of Purification - where Buddhaghosa essentially says this:
A person with equanimity, if faced with a murderer who demands a choice made between an enemy, a friend, and a neutral person - would not have a preference. The person with equanimity has an equal disposition to all form.
Also, it’s convienient to think of it this way because the near enemy to the sphere of infinite space is equanimity - and by dropping equanimity one approaches infinite space ie. “with the transcending of all perceptible forms, one enters and remains in the sphere of infinite space.”