Exactly. Take them out, keep them out.
IF (big IF- disruption is kept to a minimum by good teaching) kids disrupt, they are out for the rest of that hour. After school detention same day. Next lesson, clean slate. For something beyond disruption (swearing, truanting) they do a day in isolation. At no point have I agreed with your barking idea that they should have to do core lessons instead of others. That achieves literally nothing. I do not get to use "he missed lessons for disruptive behaviour in Science during which time he had to do extra maths" as a reason for a student missing his GCSE target grade.
Brycie, you're not a teacher. You don't fully understand how it all works, nor should you be expected to. So stop making out that you do.