Would you be ok for a dog to be free to wander the neighborhood as you notice their dog is alone, unleashed on your lawn/property?

Because short of allowing it, there's not much difference between going in person or that text(because the text was polite and they easily could of included the warning that if it continues, AC will be notified or some other heavy handed response such as pellet gun, etc).

Re the OP text, I actually appreciated the neighbor mentioning some of their concerns(new grass, kids) and not stating the obvious; AC will be called if it continues. We're dealing with serious new sod destruction due to dog urine(likely our female dog in our backyard).