I know nothing about this campaign. However, if I assume there is no harm in it, I can't see the point in NOT taking part. It's not as if they are being asked to wear rainbow laces for every match until homophobia is stamped out, is it..?
The other day there was a the squad photoshoot. In proud position was the placeard, held by Pochettino, Say No To Racism.
So where's the difference..? Don't tell me because saying no to racism is about saying no to discrimination of foreigners or people of other colours, because that is already making a distinction of difference. If you say no to racism you ought to say no to homophobia. Or have we finally abandoned the Great Big Melting Pot World..? In effect, all it is, is another minority/ethnic/cultural people being discriminated against. And that's wrong.
However, the campaign may have an agenda that isn't acceptable. I don't know.