"Layman" and gender equality

Is it correct to write:

He wants to explain X concept to the layman, not before warning him ...

Or should I write:

He wants to explain X concept to the layman, not before warning him or her ...

Solution 1:

I would suggest either using layperson and using either him or her or them which can be used as a singular.

Historically, he can be used to mean he or she, but nowadays I think it's less acceptible due to changing tastes and English being a living, changing language. I've also seen she used meaning he or she and I think that's fine but inelegant.

I would use he or she/*him or her* or they/*them*.

The singular-they has been used in English for a long time, and I think ultimately offends fewer people than just he or just she.