His employees for this tournament set out their stall for a collective of expectations for those taking part, as I guess they would with others things too such as, drinking, curfews, media responsibilities etc.
He decided he couldn't/wouldn't go along with their expectations and therefore excluded himself. I wonder if he would have had a different stance if there was an expectation to wear a black arm band in respect of someone's death.
His reasons are his, he can choose whether to share them or not, however the silence leaves a hole which others will fill, but that his choice. Often someone's silence can say more than their words.
Thankfully from a football perspective we have GS who so graciously and eloquently lead from the front on this very issue.
BLM