How do I explain it?
There is nothing to explain. The Holy Spirit does not reside in heaven. Why would he? Jesus said in John 14:16-17 that the Holy Spirit lives with us and in us forever.
Part of the point is that holy spirit is given no honor, no glory, no credit, by anyone. It's not included in the Godhead. If anyone had thought it was separate person in the Godhead it would seem that they didn't convey the respected honor or respect. And of course they didn't because the doctrine that the holy spirit was a separate person was developed long long after Christ died.