Krishna
I'm really sorry to hear your Dad is having such a rough time.
Following surgery I had a trach for 10 days, and even though I wasn't suffering from any really bad mucous issues at that time, I clearly remember how often, and unpleasant the cleaning of the trach site was.

I can only imagine what it woul be like with sticky mucous complicating the whole thing. I can understand what the Doctors are saying about complicating factors with a trach and the stoma. Again, I am sure that they know best, and if they're saying medication is preferred, I would stay with that plan. Keep being your Dad's advocate for action...it's incredibly important to him
Wayne