Yes, you are probably right, partially, however, Olga's marital situation was not exactly "acceptable" by most standards either was it ?. Even although she was forced by her mother into a marriage with a real dweasel. If one compares the drama caused by the slightest bad behaviour of any of the Grand Dukes ( banishment, allowances cut off, etc) her attitude seems a bit hypocritical. She lived in a " menage a trois", for years, and the family turned a blind eye. Many people would raise an eyebrow even today. Xenia was no saint either, was she ?
I think that if Marie Feodoravna disliked Natalia so much, she would never have recieved her, even though it only happened after the Revolution,and once in 1914. So Olga's attitude towards her was strange. But as you say, perhaps she just disliked her so much for some reason, that she denied ever having met her. Natalia was not very complimentary of the Imperial family. That could also be a reason.
I think Olga was a really nice person, who had a very hard life after 1917, but this is the only thing about her that I dislike.