Troubling situation at the tables

[Zybomb]

I wanted to bring this up the other day but I forgot about it

Monday Night I was at the "room" playin and a situation came up. I took notice, bc I had had a similiar experience (sort of)

two opponents to the flop, one was a PFRer who raised to 12 preflop. The flop came AAK. The PFRer made a small bet (these amount are what I think they were, I wasnt in the hand so i wasnt paying complete attention) of 12. It was called. The turn came a 10. The PFRer bet 15. It was called. The river came Q. The PFRer bet 25 it was called. The caller shook his head and said show me your Ace. The PFRer showed A8. The caller nodded and said "it's good"

The PFRer began to collect the chips and the dealer went to clean the cards...she had part of the flop in her hand being picked up when the caller said "HOLD UP hold up hold up, I didn't muck my hand yet" (he was still holding his cards) . The dealer dropped the cards back...He looked at the board again and said no no, I have a straight and showed King Jack... "I really didnt mean to slow roll I didnt even see it, I wasnt paying attention"

Who is entitled to the pot? Do the words "its good" constitute a muck even if the cards arent thrown away?