I don't think many people on here actually support racism or sexism though, particularly not by employers.

Sure, but it's neither racist nor sexist to say we are looking for one group of people more than another group of people. It's entirely shitty, but it is neither sexist nor racist, since they are not refusing to accept work from those people, they are simply saying they are more interested in work not by those people.

Stating or even implying a preference based on sex or race in employment is not legal for companies with more than 14 employees

Actually it is: It is entirely legal to state a preference for first refusal by a member of an ethnic or gender group by saying "would particularly like to hear from you if you are not white and not male."

That is entirely legal and not only will it remain so. it SHOULD remain so.

In both the US and Canada, if a publicly-posted advertisement for employment even tends to discourage certain applicant groups, it's illegal.

But it doesn't discourage anyone, it encourage one group. Encouraging one group is not the same thing as discouraging a different group.

Oh & for the record it's not illegal to discourage or out right declare a group should not apply, if a role requires a specific type of person: For instance if you need a male actor for a role, then you advertise for a male actor for that role. There are many positions like that that downright require a specific sort of person & it is not illegal to declare that in an advertisement for that position.

There's no way to read what was posted and not see it as discouraging certain groups.

But it's not discouraging a group, it's encouraging another group. If you are discouraged by not being given top billing that really is your personal bugbear.