In regards to your Dad rejecting Tracheostomy, I think that is a personal decision by him. Tracheostomy (also known as Vent) puts a lot of burden to caregivers and the ALS patient alike.
If I were you, I would discuss the pros and the cons of a Tracheostomy at the ALS Clinic where he attends to. Just do not forget that ultimately the decision whether to Vent or not lies on him.
I, myself haven't made any decision in regards to Vent but...whatever I decide, I hope my family will respect it.
Take care and, if you need more help just leave another message.