They should, because there are many things that we don't have sufficient evidence to prove or disprove, and sometimes it's useful to hold an opinion on them anyway.

If a person can make the unsupported claim that gender differences do not stem from biologically hardwired tendencies, then a person should be able the unsupported claim that gender differences do stem from biologically hardwired tendencies.

Also, not being able to make "unsupported" claims is a vicious cycle. If you can't say X, then any academic study is going to phrase their conclusions very careful regarding X (or possible selectively publish - I've seen this). And then X is going to be "unsupported".