Advice needed on moving dad that is in cognitive decline, living in squalor alone and out of state, to my sister's house. How can I make this move easier for everyone involved?

My 88-yr old dad moved to a very remote Texas town about 20 years ago. He is 3 hours from the nearest city/airport. My sister and I live in Colorado, a 2-day drive away.
He has been independent, mobile, and in good health until recently. His phone stopped working several months ago and my sister and I could not reach him (he rarely if ever calls us, even when his phone is working).
One of his friends got in touch to let us know our dad has lost 20lbs in the past 2 months (weight he couldn't afford to lose), seems disoriented, and claims he has no appetite. So last week I took time off work to drive down to see what's up.
He is confused, living in a trailer in absolute filth with no running water, mouse droppings everywhere (including inside his fridge), and he's an absolute skeleton. Also incontinent and unaware/uncaring. Thank goodness I got his signature giving me medical and durable POA while I was there. I kind of forced him to go to the local clinic, first time for a checkup in over 30 years. Although he is wasting away, his bloodwork suggests no major physical issues except dehydration. But he scored 0/5 on the cognitive assessment. His memory is shot, e.g., he can't remember my mother's name (his ex-wife) nor conversations that happened earlier in the day, and obviously he's forgetting to eat too. And he still drives (!!). Doc said he should not drive and shouldn't be living alone. He has VA benefits but we're not sure if he has Medicare. I paid out of pocket for his clinic visit and labs. There is no VA where he lives and he has said that if he ever needs medical care to take him anywhere but to the local hospital. There are also no assisted living facilities and no home health care services, outside of meals on wheels which he refused.
My sister has invited him to move in with her for a while, at least through the winter, but he refuses. All his friends suggest we just put him in the car, tell him we are going on a short trip, get him a milkshake, and then drive him to Colorado. Basically, kidnap him. He likely wouldn't notice given his current state of mind, but he is actually lucid about 50% of the time and will of course notice at some point. They also suggested we tell him that it's only temporary, that he should come hang out with his kids for a few months and once it warms up again in spring we'll take him back to Texas. Once in CO, we will take him to the VA for a more formal cognitive assessment and likely plan to find a local memory care place for him near to us, since it seems his body may outlive his brain.
My sister is making arrangements now to move him in. She has a one-way flight and a rental car lined up to get herself there, pack up dad and some of his stuff, and drive him back to CO. We sent Medicare his info and proof of POA and we should have access to his benefits soon. We are kind of in a state of shock and not sure how to navigate getting dad here, but he absolutely can't stay where he is. He is very docile, so we don't expect him to physically protest, but we're not sure how best to navigate this. It's happening so quickly. Any ideas/suggestions would be appreciated! Thanks for reading if you made it this far.