The United Nations Convention on the Rights of Persons with Disabilities defines disability as:

“long-term physical, mental, intellectual or sensory impairments which in interaction with various barriers may hinder [a person's] full and effective participation in society on an equal basis with others.”

So no. Having a dominant hand is not a disability. Most definitions agree that having a disability means being unable to perform major life activities without accommodations. Being right- or left-hand dominant isn’t a disability really by any serious definition

And frankly, what you’ve posited is a little offensive. It’s bs like this that presents barriers to getting support for people who actually do have disabilities