This could be more charitable. The very first sentence of the linked article says "less likely to play with boys' toys like cars or to join in rough and tumble games", so it would be reasonable to assume they're talking about behavioral changes is that vein.

So to be completely fair, I'd break it up into two parts:

1) Given our current understanding of endocrinology, anything that alters the hormonal balance of children is probably not what you'd call a "good idea".

2) However, if something were to make the behavioral patterns of male children more closely resemble those of female children, that effect might not be bad for a society.

And I'll put forward, hesitantly, that the strong pushback against this idea has less to do with the obvious (1) and more to do with the deeply controversial (2).