You are correct that you can (currently) transfer back to CSUN, with minimal risk due to comp sci not being impacted. That said, assuming cost is not a significant factor, I think you need to decide which is more important to you: your major or the school you attend.
If the former, your probably better off staying at CSUN and attempting to transfer into a UC directly. The major is not as impacted in CSUN and you won’t have to deal with the headache of getting the necessary Comp Sci prerequisites at a CC.
On the other hand, If you value attending a UC over being a computer science major then the risk of an extended stay at a CC and / or eventually transferring in as a non-comp sci major seams manageable.
Also while Pomona does give TAP “consideration”… past admissions results only average around 18-20 transfers per year with the majority of them coming from other small LACs. TAP consideration for Pomona (or any of the 5C’s) is a very small piece of the puzzle and one that, logistically, shouldn’t even be factored into your decision of whether to go to a CC or not.