Avira, thanks for the ref. to YD. How do you understand Shach there? He appears to interpret the chochma as studying esoteric subjects, including Kabbalah as opposed to, or before, halakha.
A couple of notes comparing with modern “chochma”:
1) By Rashba, it would be OK to study anything not avoda zora as long as it is not a fixed occupation. I would say, someone who has enough money to live and then makes studying Chinese philosophy his daily routine after shacharis would qualify. But would you say that taking a semester class is not temporary?
2) Often, one can gain indirect understanding of Torah and ability to argue for it from studying surrounding materials. I think R Ovadia Yosef explains Rambam this way – that all philosophy that Rambam learned was for the glory of Torah. Take an example of someone who works in academic environment and meets western-education public. He needs to know a lot not just to protect himself from their argument but also to explain them Jewish positions.
3) A lot of current “education” is really job training. 99% of professors are not aware of Aristotle, unless this is their direct line of work. The liberal stuff that is being injected in every subject is not “chochma”. Propaganda may be more dangerous than chochma, but off topic for this thread, I think.