They are saying that those of us who critique the case for deferring to preferred pronouns (i.e. "Be nice!") ought to critique the "Pronouns are Rohypnol®" argument as well.
I don't get the sense that Ms. Kerr was making an argument that we have to conform our usage to hers, though:
If you do this experiment you may still decide to accept or use female pronouns for male people, perhaps a little wiser, but cognisant of their influence on you and others. That’s a choice you may make. At least now you understand that you may be voluntarily suppressing your own natural response. Your eyes are more open.
Instead, she was arguing that females ought not be expected or coerced to change the way they use pronouns, for various reasons. I'd say there is a significant difference between asking for tolerance and demanding conformity to "correct pronouns" but don't expect others will see it that way.