Sounds cruel, but it is her wedding and not a chance for Grandma to be distracted by some kids.
That does sound terrible given the circumstances, but wouldn't there be enough family around to take care of her? Wouldn't she already be distracted by the wedding and gorgeous bride? Why is there a fight about what grandma wants AND NOT YOUR FUTURE WIFE ON THE MOST IMPORTANT DAY OF YOUR LIVES!?!!?! (these are the thoughts probably going through her head).
But, if everything is in cammo, maybe she can't see anything else to be distracted by.