Given the clinical data you present they may discuss systemic therapy.

Since he is on ADT to lower his T and begin reducing tumor burden, there may be discussion about potentially adding an ARI.

Unlikely from you describe as his health would chemotherapy or radiation come into treatment discussion. That's not to say no, radiation could be used in selected locations to reduce tumor burden and the pain from those. Chemotherapy can be hard and are and fitness to go through it are important factors in that decision.

There are other agents which may come in to discussion which have been mentioned here though sometimes they are FDA approved for metastatic castrate resistant advanced prostate cancer which the clinical data you describe doesn't indicate he is.

The issues of overall health may come into play in the treatment decision as well as your father's preferences. Some mentioned palliative care. As discussed, it doesn't mean no care, may simply avoid the heroic measures.

It may seem like an oxymoron but he may be off to a "good" start, his visit to the ER, the labs and imaging, oncology starting ADT and follow on discussion with a multi-disciplinary team and YOU!

Kevin