The holy spirit does not dwell with those who do not acknowledge him.. And without baptism, he is there some times. When baptised, you have the constant companionship of the Holy spirit. It is A gift we receive when we follow Christ in our heart. And obey the commandments.
The question of baptism is a moot point.
Various churches recognise different forms of baptism.
Trinitarian churches do not recognise the baptism of Mormons, JW's and Unitarians.
Nor do JW and Mormons recognise other churches baptisms.
I have no reason to suppose that God does not recognise them all equally.
The earliest teaching on baptism that we have is to be found in the Didache where it allows for various ways of performing it, from total immersion in flowing water, to the pouring of water on the head. These recognise the various difficulties faced by desert dwellers and the sick.
Many churches perform Chrismation where the child is anointed with oil following baptism, It is done in the name, and in recognition of the Gift of the Holy Spirit.. This is done in all Orthodox churches and some Anglican churches, including my own.
However the Holy spirit is with us from Birth or even conception, depending when you consider quickening to occur. Baptism and or confirmation certainly enhance our recognition of this. But that is from our perspective.
From the perspective of God and the Holy Spirit we are all equally their concern, baptised or not.
If you believe in universal salvation, and Mormons certainly believe that all have a opportunity after death to accept God. Then it stands to reason that the Holy spirit remains with us all during life baptised or not.
It is rather harder to say what the actual Affect of baptism is, and few churches define it, though most do see it as a public membership ritual of some sort, and a calling of the Holy spirit to support that person.
however that seems to be more for the benefit of the candidate and congregation, than the Holy Spirit, as he will do so anyway.
We are commanded to be baptised in much the same way Jesus commanded us to remember him in the Eucharist.
These are the only two rituals we are commanded to follow.