Of course, if he has a better option, he should take that. But I’m assuming that if he had a better option for a STEM teacher rec, he wouldn’t have asked this teacher, the one who was unhappy with his having not prioritized doing the homework assignments. I mean, who would go to a teacher for a rec after having blown off the homework, if they had a better option?
It’s something that a lot of students don’t think about, until the beginning of senior year. Teachers are human - you cannot blame them for reacting this way when a kid who all year sent them the message that their homework assignments weren’t important, then asks them for a recommendation.
I feel bad for the student, too, because I totally understand a student who is extremely busy with other work and ECs prioritizing those over the busy work, especially if they have already mastered the material and can demonstrate it on the exam. If that student can get a recommendation from an AP science or math teacher in fall of senior year based upon two months of excellent high performance, I think that it should be okay. It may even be a teacher who already taught them earlier on, or with whom they’ve had contact through an EC. But even if the teacher has to check that they’ve only known the kid for 2 months, it’s still a heck of a lot better than a rec from a teacher who has flat out warned them that they’re going to say something about the undone homework assignments!