I wouldn't put too much on it, I would have prefered that than a groin strike etc.
The thing is on a self defence situation, this day and age the Bad guy can also be the Bad woman and as you know a grab/strike to the breasts is rather painful if fully applied. It was natural instinct, there was no giggling or embarrased attributes to ascertain if the boys were "trying their luck" if you understand what I mean.
I would recommend trying the same technique but recommend alternative areas to grab etc to assist them and save any embarassment. Do you have a male Teenage Cadet leader etc who could assist you with this particular technique?
A man is but the product of his thoughts what he thinks, he becomes.