Check out the public beach at Inlet Beach. There is a long ramp (I don't believe there are stairs), the beach is wide but not deep which means your dad won't have to go too far to get to the water. Or, he may want to stay near the ramp and he'll still get a good view of the water. The life guard station is near the ramp. If High Point is in the Seacrest Beach area, Inlet beach is closer than Seagrove. Just go to the end of 30A, turn right onto 98, go about 1/4-1/2 mile and turn right. That will take you right to the beach with parking and bathrooms. I don't know if a beach wheelchair is available, though. If you're in the Rosemary Beach, Villages of South Walton, and Alys Beach area, it will be relatively easy to get around those communities. There's a walking trail at Alys beach that may be wheelchair friendly and is about 1/2 mile long through the native environment. I believe it is or mostly paved/level.
By the way, we have a friend who was diagnosed with ALS in his 40s and his friends created a foundation to raise money for research. He's doing pretty well under the circumstances, and is married with two young children. Here's the Facebook link and on it are two videos about 5 of his friends, (women, mostly moms with jobs and kids at home) who decided to swim the English Channel to try to break the world record to raise money for ALS. Non professional swimmers, they did it! Great, heartwarming, inspiring, sometimes funny videos, professional done. One of the swimmers was diagnosed with breast cancer part way through the training for the swim, and continued even more devotedly with the swim. One of the other swimmers said her young daughter now things that when you get cancer, you swim the English Channel! Here's the link in case you're curious about these inspiring videos:
https://www.facebook.com/pages/Channel-for-ALS/217346511634247 .
Enjoy the beach and the area!