It has been said that just because something happens in the Bible doesn't make it a rule. The fellows who were baptized in the name of Jesus, yet hadn't received the Holy Spirit, it seems were an exception - God can do that...

Actually the part of it that strikes me as likely to be an exception is the laying on of hands.  I haven't had enough time to study afterwords but the next thought that came to mind was the following.  I almost typed it in the original post but was/am still mulling it over but figured I should add it for clarification now.

That was Jesus speaking of course.  So you accept Jesus.  Jesus does not "morph" into the Holy Spirit.  I say morph because, being honest, that's how I always had pictured this in my head.  Jesus knocks, you answer, the Holy Spirit is at the door and the one who comes in.  Rereading the verses, that does not appear to be the case.  Nor would it make sense if it was the case (why the morph?).  What would initially appear more logical is a 2 for 1 deal.  Jesus knocks, I answer, He tells me this is a "2 for 1" deal as far as who comes in.

However I say initially.  And that's because I want to get the Holy Spirit in there as quickly as possible.  More things bouncing around in my head though that lend towards there actually being a delay.

At what point did the thief on the cross receive the Holy Spirit?  And did he?

At what point were the disciples saved?  Because based on Jesus's comments the Holy Spirit wasn't around (at least for the disciples) during the time He was on earth.

I reread the whole chapter and I think it's directed at the unbelievers.  Because it seems to be directed at what causes people to be believers. 

What would happen if someone didn't open the door?