There's a good reason for that. Specifically, that there was no racism directed at Rudiger. I am 99.9% certain of it. I should know.......because I am one of the fans, I believe, who is responsible for Rudiger's accusation. I was at the very front of the south stand, adjacent to where the Son sending off took place. There can't have been a fan in the stadium who was closer than me to where it all unfolded.
By way of background, for what it's worth, I have no real argument with Son's sending off. He did make a slight, if aborted, move of his feet towards Rudiger as he tumbled. Silly, spur of the moment action that, in today's game, will always result in a red card if spotted. Nevertheless, that can't excuse Rudiger's reaction. Mourinho said it best when he sarcastically wished the Chelsea defender a speedy recovery from the multiple broken ribs that he must have suffered. There is nothing more cowardly within football than feigning injury in order to get an opposition player sent off.
So, as English football fans are wont to do in such circumstances, we all chanted "cheat, cheat, cheat, cheat..." at Rudiger. It was at that specific moment that he turned and gestured angrily at us. And immediately went to his captain / the referee to complain about having been the target of monkey noises. So I am convinced that this entire controversy is based on a misunderstanding on Rudiger's part. When English is not your first language and when you are unfamiliar with English fan culture, 5000 or so English fans chanting "cheat, cheat, cheat...." unsynchronised could, I suspect, sound very much like monkey noises. The timing of Rudiger's angry reaction towards the fans and immediately subsequent discussions with the referee confirms that suspicion. The only alternative is that Rudiger is claiming that he heard a lone voice making monkey noises. And if that is the case, then I say that Rudiger is a liar. Not the remotest chance that he could have isolated that above the din of 5000 fans shouting "cheat".
Spurs, and specifically Spurs fans, are owed an apology.