Perhaps it is driving the principle too far to say that Being with God is less than Being with Self?
It is something which depends on the way we understand this statement. If we give-up our own individuality in order to be God's own Self - as some, it seems, are trying to do - we simply become God's own Self again, and lose our own identity. This means we are no longer in the context of the statement anyway, as there is no Us anymore.
If it is a temporary at-one-ment, we can absorb a lot of God's presence quality, and therefore grasp the way His feelings and mind work...
We may still feel that we can know us-being-ourselves better than we can know God being God. It's the Teacher/ Pupil situation again, in which the Teacher wants it to become the Teacher/ Teacher situation - as Friends.
This short statement by William Arkle seems to highlight the problem with aiming at oneness with God (or Deity); as so often advocated by Eastern-Influenced spiritual people nowadays; including many self-identified "Christians" whose implicit aims are actually oneness, rather than resurrection and Heaven.
The problem is that if oneness with God is achieved, then we are no longer ours-selves, and therefore are no longer a part of the situation (the "context of the statement").
And therefore aiming at oneness is a species of the mainstream atheistic assumption that this mortal life is destined for annihiliation. Oneness spirituality may amount to little more than positively embracing the unavoidable annihilation of mind and body posited by secular materialism.
[Which may be why mainstream secular materialism - even globalist totalitarianism - is happy to advocate and support oneness spiritualties - such as 'mindfulness' and (Westernized versions of-) Buddhism, Hinduism and the like.]
But Arkle also mentions that a temporary, and somewhat incomplete, enhancement of oneness; can be considered a way of learning more about God's nature and motivations.
In other words, some partial elements of the kind of passive, immersive, un-selfing, not-thinking meditation advocated by oneness advocates; can be a way of getting-to-know God better.
A good old-word for this is communion - and may lead to making a useful distinction between the Christian seeking of comm-union with a personal God; and the "Eastern" aim of union with an im-personal God (Deity).
The value of communion is obvious*; even when it occurs on the way to a temporary state of experienced-union - which by definition (if complete) is not experienced, neither is it remembered - because there is no Self either to experience or to remember what has happened.
Therefore communion with God ought Not to proceed to union, assuming we desire to learn and benefit from our knowledge of God.
Union is good only for escaping from our-Selves, since it annihilates all experience of being...
*I would go so far as to say that nothing is more valuable to a Christian than a solid and faithful knowledge of God's nature and motivations; since this can serve as the basis of discernment and guidance though all manner of confusions and deceptions; including those propagated by the Churches.