There's also a sensible middle ground. If OP's father weighs 350lb, they could do the feeding tube port and use it to give him low-calorie, high-nutrient & mostly liquid food to keep him hydrated and keep his digestive system from shutting down while he loses weight. If he (partially) rebounds after a week or two, your problem is solved -- he can tell you himself what kind of care he wants going forward.
Lots of people screech, "No feeding tubes, ever!" while they're healthy, but VERY FEW people ever demand their removal or non-use once they're in place and/if they regain lucidity. It's a well known phenomenon -- people set arbitrary lines they swear they'll never cross, but as lucid death approaches, those lines keep getting pushed back because they themselves decide that continuing to live is, even in a compromised state, is preferable to death.
It's different when someone is in 24/7 excruciating pain, like death from liver cancer, but most end-stage conditions ebb & flow... and the ebbs happen just often enough to convince them that getting to the next ebb is worth enduring the current flow. There's also a tendency to hang on until some upcoming event before voluntarily throwing in the towel & saying 'no more' -- Christmas, 100th birthday, child's wedding, grandchild's birth, etc.
The downside is that it's also common for people to hang on until a day like Christmas, hit the day slightly disappointed when it ends up sucking in their current state, end up in the hospital on a day when it's overcrowded & understaffed (often, after procrastinating because they didn't want to ruin anyone else's day), dying, and ensuring their loved ones' Christmases will suck for decades because they died on a date that literally CAN'T be forgotten. And for some dying people, that's actually comforting. Everyone is different.
To me, it sounds like OP's dad is the type who'd protest in advance, but decide to hang on anyway & push back the goalpost another 10 yards (for now, at least) if he woke up & found he'd been moved to the next step while asleep. Especially if he wakes up feeling kind of good compared to how he felt a few days ago (lungs freshly vacuumed out, painkiller euphoria, and 25-50lb lighter).
My mom terrifies me. She's in good health now, but she's precisely the kind of person who'll happily "go to Jesus" at the first opportunity if we don't try to at least throw a speedbump or two in her path. I had a MAJOR argument the last time she had relatively minor surgery (knee replacement) because she completely HORRIFIED me by casually checking "DNR" without a second thought.
I can see someone getting worn down by pain & hopelessness, but I'll be *damned* if I'm personally going to ever voluntarily die out of the blue from something stupid without putting up a good last-minute fight first just to be stubborn.