This strikes me as well-intentioned but vaguely…misguided. From A Dream Takes Root: Treehouses for Kids With Disabilities:
Mr. Allen is the founder of Forever Young Treehouses Inc., a nonprofit group that builds handicapped-accessible treehouses in camps, treatment centers and parks. Started in 1999, the organization has built four such structures, three in Vermont and one in Connecticut. Work has begun on a fifth: a $100,000 treehouse at the Crotched Mountain Foundation in Greenfield. It’s a treatment center for people with disabilities, including Ms. McIntosh.The steep price reflects the difference between a garden-variety treehouse and one that’s accessible to wheelchairs. A Forever Young project includes two structures: the treehouse itself and a very long ramp that climbs gently from the ground into the forest canopy. The treehouse must be able to support both the children and their wheelchairs, including some motorized models that weigh 400 pounds. The ramps can be as long as a football field.
[...]
Mr. Allen says Forever Young is rooted in his own childhood love of treehouses. “I just think it’s a raw deal for a kid to be sick or disabled and not be able to play in trees,” Mr. Allen says.