I also doubt this incident ever happened. Firstly, even if Maria was a flirt and naive, I seriously doubt she would have been so indiscreet and bold as to have let herself been caught kissing this man. She still knew her limits. I think, like all her sisters, the girls were really quite shy, modest, and innocent in their dealings with men. They probably had schoolgirl-type crushes on them but tried to keep their emotions in check around them, and some of these young men perhaps didn't even know they were the object of their affections. They preferred to confess their crushes amongst each other or to their diaries.
Secondly, I also agree she wouldn't have argued with her mother about it. Her parents knew about her crushes and thought them merely amusing, and even teased her about them, knowning they were of course nothing serious. So I don't think Alexandra would have made a big deal about it. I have read that when Maria was eleven, her mother found out about a crush she had on a soldier. The only thing she wrote to her daughter about it was: "Try not to let your thoughts dwell too much on him, that's what our Friend said...I know he likes you as a little sister, and would like to help you not to care too much, because he knows you, a little Grand Duchess, must not care for him so...Be brave and cheer up and don't let your thoughts dwell so much upon him." That's a pretty mild and gentle scolding.
