Multiple cats in home. One cat on Palladia for mast cell tumor. Need advice.

Hello, I have 4 cats in our home, multiple cat boxes in home and all cats have free access to all rooms of the home. One of our cats was recently diagnosed with a mast cell tumor and has been placed on Palladia. Cat boxes are cleaned daily.

The cat being treated has been staying with a friend because we are worried about cross-contamination with the drug via feces and urine amongst the other cats in the home. Unfortunately we need to bring him back to our home today due to complications with said friend. Our plan is to keep him confined to his own room in the home with his own litter box and feeding area to avoid cross-contamination.

My question is, how necessary is this? Am I over-reacting or am I taking the proper precautions? Will we be okay simply letting him roam the house freely and cleaning the boxes daily? Is there anything else I should know? We can't get a straight answer from our vet. Thank you.

*Edited to fix typos