I was looking at the scooters and the one that looks the most comfortable is for 500 pounds dh weighs way less then that so my question is would it hurt if I got him that one
It just looks the most comfortable out of all the other scooters and want him to be comfortable I know that sounds trivial
It doesn't sound trivial at all. You want your DH to be as comfy and happy as possible!
Having said that... remember that often bariatric equipment (generally speaking, items made for people over 300 pounds) will not feel as comfy to a normal sized person. In fact, they could be actually uncomfortable.
This is because those items (especially things like seat cushions, mattresses, or furniture, etc.) are often designed with different types of foam, fabric and fillings to accommodate a person of a larger size; normal size adults may find that to be uncomfortably stiff or firm. Additionally, seat lengths tend to be longer, which means that a normal size person may find that the backs of their knees will not bend so that their feet can reach the floor unless they scoot farther forward on the seat - thereby losing any back support.
Finally, armrests are often uncomfortably far apart for a normal sized person.
Work with the rental company that you chose to use directly to find the best scooter for your DH. They are experts - they rent these out every. single. day. and they know what scooter will fit your needs better than anyone else. Tell them where he hurts/has problems (for example, his back hurts, and he can't lift his feet very far off the ground) and they may ask you his height and/or weight. Be honest with them, and they can then recommend the best scooter for his needs. Be sure to ask them if he finds it uncomfortable, can you swap it for a different style/model.
I promise - use a reputable vendor, be honest about his needs - talk to them on the phone; don't just try to email or chat someone - and they will find you the best possible "fit" for your DH.