In "Harrison Bergeron", why don't George and Hazel think much about their son even though he has been taken away?

Remember that in this terrifying vision of a dystopian society,
the big equalling factor is that everyone by law is required to be the same as everyone else - no
one is allowed to be better or more intelligent. Thus, when the narrator tells us about Harrison,
Hazel and George's son, being taken away, he then goes on to explain why his parents are unable
to think about it and get upset about it too much:

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It was tragic, all right, but George and Hazel couldn't
think about it very hard. Hazel had a perfectly average intelligence, which meant she
couldn't think about anything except in short bursts. And George, while his intelligence was way
above normal, had a little mental handicap radio in his
ear.

This handicap, the narrator goes
on to inform us, would send out a sharp noise every twenty seconds or so, meaning that George is
reduced to "average" intelligence. It is because of this that Harrison's parents are unable to
think about him and get upset about what has happened to their son.