World hijab day at the nursery

My son has been attending this nursery at Camb via the University since he was 9 months old and we have has absolutely no complaints re. the quality of care and such like since. He is now almost 2 and the quality of care and service has continued to be exceptional. I have continued to ignore the stress put upon halal food etc. although I don't quite agree with it. Today I noticed a banner on the nursery notice board celebrating something called "world hijab day". Not only do I detest this purely out of the ridiculousness it implies and nonsecular nature of this "celebration", I do not want this sortae thing to be normalised for my son whilst growing up. My partner said I can't raise this issue with the management since there's a risk we might be thrown out of the nursery because raising an issue such as this portrays me, the primary parent, as intolerant, boder-line racist so on and so forth. We obviously can't risk him being chucked out since we have no other choice, but I honestly ask you all, is this acceptable? Are we at this point where I can't even make my point or express my view lest we suffer dire consequences? In our own country? How does this promote equality or diversity? This is madness! There's a limit to this idiocy. Is there something you all can suggest I do regarding the above?

Edit: When I went back this evening to pick him up, the poster was gone, and that settled it for my partner. I've been reading all your replies all day. Thanks a lot for your support, and I honestly had planned to have a chat with the lady in charge. However, since it was not there anymore, I decided to leave it be. But still it is bothering me quite a bit, and I've decided, quite against my partner's feeling about it, to have an open and calm discussion about it with the management. I am, afterall, paying almost a month's rent to have my son looked after to the highest standard of care, as defined by the university, and I believe that allows me to have a say in what environment he is exposed to. I shall update you all regarding the outcome. Also, as you all mentioned, reporting to the news is not off the table. Thanks very much for that idea.