It seems to me that your understanding of Gandhi is very limited based on a very cursory reading of shallow accounts. I urge you to read more about him to gain a deeper understanding of the man that he was. It would take you a life time though to get an understanding of a deeply complicated person he was. Visit the library at the Sabarmati Ashram if you have a serious interest in knowing rather than speculating.
He would be the first person to accept he was flawed. And he has written extensively about it. His views on race evolved. He sure had a different point of view while living in South Africa at a time which needs to be taken into historical context. His primary interest as a lawyer was addressing the issues Indians were facing.
Even Einstein seemed to have had some racist views about the Chinese we have recently come to know.
His experiments with sexuality were troublesome and many around him found it difficult to accept. He was married when he was 13 and in a very conservative family in a time you can barely imagine.
He had a purpose behind his personal experiments which are complicated to understand and yes difficult to accept. You can read a first hand account of his niece Manu, in her recently published diary if you seek a deeper understanding.
Gandhi would be the first person to accept and acknowledge his flaws. He was constantly trying to be a better person. This is what makes him a Mahatma. Not his politics or his views or "great achievements".
Gandhi lit the spark which brought an end to global colonialism. People of all races benefited from it immensely. You cannot even begin to put a number on how many people he would have impacted world wide.
To look at him in such a narrow manner does great disservice and is frankly insulting. People of color in America today enjoy the freedoms as he inspired Martin Luther King. Mandela fought for the freedom of his people inspired by him. His picture hangs in Obama's living room. So on and so forth. He needs to be given immense amount of slack just because for this. Are you saying these people just admired him for no reason or are misinformed?
No prize exists that would be worthy of him. He was a giant. Him not getting a Nobel really means nothing. He did not need affirmation from the west to be be declared a Mahatma.