Oh you are so misinterpeting the meaning of God’s omnipotence!
To say that porn comeing from the free will of man is of no consequence is totally fallacious. It is the misuse of free will that is the crux of the problem! The misuse of free will is what causes man to sin. Sin seperates man from God. How does God bring about a greater good from the misuse of free will? Does He intervene? NO, He does not. He invites man to make recompense and the first step is Reconciliation, through which man can recieve forgiveness for his transgressions and be put back into a state of grace. Reconciliation is another exercise of man’s free will.
Read 2 Peter 3:9 which tells us that *“The Lord delays not his promise, as some imagine, but deals patiently for your sake, not willing that any should perish, but that all should return to penance.” *
As for God’s omnipotence, God cannot transgress His own nature. For Him to do so would mean He is not a true and faithfull God and I’m even sure you would accept that. If God were to impose His will onto the free will of man, He would be acting in a contradictory manner and God cannot contradict Himself without acting contrarily to His nature, which is all Good.