Act of stupidity given the venue yes - deserved to go - no.
To be fair to the lad, he's not from round these parts and hasn't been here long so he probably doesn't know how it works up here. Killies fault for not briefing him properly. You just need to see the look of incredulity on his face as he comes off the park to know he's not done anything untoward.
Morelos law from day one this season states that unless its an act of "violent aggression" and/or "brutality" then its not a red card.
Never in a month of Sundays can that be classed as either.
His stupidity was to use an arm and not choose to kick the boy or grab his ball sack as that's clearly all fine...