There are several considerations to consider.
First is, I have never been successful at asking a fox for its sex before shooting.
Second, I don't like the reaction of farmers when I tell them they have to continue feeding cubs.
Third, I don't have an issue with others shooting milky squirrels, rabbits or rats and not showing any consideration for any lactating young.
Fourth, the cubs in this case most probably have pa and an aunt to fall back on. They are not reliant on milk by the end of April.
An ancient proverb, "let he who is without blame cast the first stone".
U.