I totally agree, I think advanced and standard math are different enough that there's no guarantee that someone will do better in standard (I know I'd probably do worse in standard than advanced due to the nature of the content) - and also, the teacher should be supporting the student! maybe every school has different difficulties of exams, but at my school only if someone was getting below 45% honestly would I recommend dropping
on the other hand, I do know people who dropped to standard and greatly appreciated the drop in workload and some went on to top the course, so maybe 
@Study to success would prefer that. but don't drop just because the teachers are telling you to