Three points:
1. Peters vision occurred anywhere from 10 to 20 years AFTER the death of Christ. Peter was a direct disciple of Christ. He knew what Christ taught. Yet:
Act 10:14 But Peter said, Not so, Lord; for I have never eaten any thing that is common or unclean.
So Christ didn't teach it.
2. In the vision, despite being told to, Peter NEVER ate. He didn't do it. He wouldn't do it. Did God chastise him for it? No. Did God judge him for it. No.
3. What did Peter think the vision meant?
Act 10:28 And he said unto them, Ye know how that it is an unlawful thing for a man that is a Jew to keep company, or come unto one of another nation; but God hath showed me that I should not call any man common or unclean.
Nowhere in scripture does anyone EVER suggest another interpretation of Peter's vision. Even when he told other's of the vision nobody, NOBODY, understood it to mean that they could now eat foods like pork and shrimp.
Again, only revisionist interpretation done through the prism of tradition allows the view you have.
I would offer dittos to your other observations ... the only hint we have that Peter strayed from strict observance is the scene where he sees Paul approaching and gets up from eating with gentiles and moves to be with observant Jews. That episode, btw, probably happened within fifteen years of the resurrection. Again, Gary Habermas has done superlative work as an Historian int his area.
Additionally, Peter is associating with the very observant brother James, so it is likely that Peter remained faithful to Jewish traditional observances throughout his life.