Go with the Guardian. It is a no-brainer. Guardian is a mutual company with significantly higher financial ratings than UC. The fact that UC is willing to compromise on the term sale (give you a certain rating that you may or may not qualify for) should be enough to tell you why their ratings are lower. There is no mortality (chance you will die) change due to the fact that you have DI with them. This type of discounting across personal lines (life, DI, LTCi) as opposed to PC lines (car, home, etc) shows that the company is just trying to collect more in premium at the expense of proper actuarial underwriting. Take the Guardian knowing it is by far the superior choice.
There is no doubt that Guardian is a fine insurance company and would be my choice for coverage for someone who is in good health who is looking for a large face amount of Whole Life coverage. However, Guardian is not in the final expense market and would decline someone on oxygen. Final expensive is a market that will usually be a small amount of coverage usually in the $5,000-$15,000 range with some companies going up to $25,000-$30,000. The smallest face amount that Guardian writes I think is something like $75,000. Guardian is a great company but inappropriate in this situation. Listen to JD. He knows what he is talking about. Delfina doesn't have a clue.