From what I've read he knew he had permission from the record label, and knew he didn't have Coolio's blessing. I wasn't there, but it seems unlikely that if he immediately had turned around like "wow I didn't know" the so-called beef wouldn't have lasted years until they made nice.

From: https://www.yahoo.com/entertainment/bp/coolio-did-not-want-w...

>Coolio said when Weird Al initially requested to remake the song, he said, "No," but later realized that, due to the fair use copyright laws, he could not stop the production.

>Coolio later reconsidered Weird Al's proposal. "I sat down, and I really thought it out," he told the students at IPR. "I was like, 'Wait a minute.' I was like, 'Coolio, who the f—k do you think you are? He did Michael Jackson. Michael Jackson didn't get mad.'"