So besides the fact that he thinks getting closer to the girls will set him on the path towards a death flag, partway into the chapter he mentions how these monsters are a helluva lot stronger than they should be. So it's a bit more forgivable because he thought he legitimately didn't need to take part in what is supposed to be the game's tutorial fight. But of course conscience comes first, leaving him to rush in regardless.
Al seems to also underestimate his own agency under these circumstances, cause he's still thinking of it like a game with a predetermined story. As the saying goes, "the only way to win is to not play," hence his desperation to stay as far away from the events of the story as possible. He's fixated on "Alba dies at the end of the game" to the point he doesn't fully comprehend how his behavior is changing the factors that led to Alba's demise in the first place.