Will a father fall into disbelief if he places the toilet facing the upper wall, intending it to be in a direction other than the Qiblah, after a verbal argument about changing the direction of the toilet in the bathroom?

What your father said is not disbelief (kufr), and it appears he said it sarcastically, as a retort to his wife. The correct view is that there is no harm in facing the Qibla or turning one's back to it when relieving oneself in covered places like bathrooms. This is permissible inside buildings according to the consensus of the majority of scholars. We advise caution against obsessive whisperings (waswas).