Its good to see your dog being so social. But most dalmatians are welcoming & playful. Wont bark/growl unless challenged negatively.
That being said, it's not that they arent good guard dogs. Any suspicious activity & they will be at the tip of their toes.
You could still train the dog to "leave it" or refrain from accepting food from strangers. Also can train your dog not to seek strangers attention by training them not to climb, etc..
Youtube has videos related to leave it and other stranger situations.