Out come a troop of wicked, mocking children.

Elisha is not bald, for he is a Jew, nor, even if he had been bald, could these children have seen it, since his head is covered; but they wish to annoy and to insult the holy man, so they cry after him, 'Go up, thou bald head, go up.' They simply use a common term of reproach.

To have a bald head was amongst the Jews a sign that a man was cut off from his nation, that he was counted as a Gentile and an outsider, and therefore to call a man 'a bald head' was equivalent to calling him a Gentile dog and an outcast.
Now Nehemiah inflicts this very punishment on these Jews who have married heathen wives.

He commands them to be made bald, as a sign of shame and disgrace.

It was a very significant and appropriate punishment.