I see your point. It's also possible Tal thought such a speculative opening was worth a shot against his younger opponent. Miroljub would have beeb about 16 at the time. I was unable to find out if Miroljub is any relation to Petar, though they're both Yugslavian (Serbian today for Miroljub).
I thought maybe Tal's 2.f4 was a mouse-slip. But of course, it's 1963, and the only mice back then were the little furry rodents, and that guy running Disneyland, Mickey.
I found tournament details in my database. Indeed he was GM Petar Trifunovic, who drew all his games as Black, excluding the game against Tal, which he won. With white he had seven draws, two wins, and one loss (against tournament winner Viktor Korchnoi).
White must be crazy to play the King's gambit to avoid a Petrov. No-one heard of the Cochrane Gambit? Or just the standard lines of the Petrov give a great position for white with subtle pressure.
I heard my 1800 rated friend mention that before, but don't know the lines to it.