Disability Rights
By all means use the elite line. If questioned say it is a disability accommodation. If questioned more, cite the Americans with Disability Act.
Alternately, use a porter from the time you get there, who I expect will just push you to the head of the line.
Exercising rights should create satisfaction and just a bit of entitlement, not guilt!
BTW, though I don't have a mobility disability, I do have a disability and do rights advocacy, here in California and elsewhere. (No, I'm not an attorney.) And there is a disability forum here on FlyerTalk if you need responses from people with first-hand experience.
Sylvia