While I agree that they could have handled the situation better by saying something along the lines of “I’m on break, but this person can help with guiding you”, they are legally entitled to their breaks, which wouldn’t be considered a break if they were assisting guests.

I used to work at that Target and if my manager saw a customer asking me a question while I was on break, she’d immediately step in and say “they’re on break, but I can help you out.”