akuperma > rabbanim cited in the Talmuds
with all seriousness, there should be no question that all of this is permitted for some. Raban Gamliel had same number of students learning Torah and Greek. I presume the equal number is symbolic here, same as 10 commandments divided in 2 groups of 5.
It is really a practical question – how much of including non-Torah material will destroy Jewish life as we know it. The answers swing over time.. When our communities were secure, you can do more; when not, you need to protect more. Unfortunately, both sides sometimes do not talk directly to the issue but try to strengthen their rhetoric by claiming that something is verbotten or, opposite, a mitzva.