Republicans who don't want their kids to see Obama's speech tomorrow can't be blamed at all. It is a speech about the importance of staying in school and getting a good education.
Being well educated might arm children with inquisitive minds and critical thinking skills sorely lacking among many of today's conservatives. Being well educated therefore reduces the likelihood of them voting Republican once they're old enough.
Who can blame Republicans for not wanting their children to watch Obama's pro-education message? Education is not a conservative value.