Short answer: No. Federal law waives the 24-month waiting period for ALS: Medicare entitlement begins with the first month the person is entitled to Social Security disability benefits.
42 U.S.C. 426(h) says entitlement begins “with the first month (rather than twenty-fifth month)” for someone medically determined to have ALS. The person still has to be approved for disability benefits.
If the person still has an employer plan, ask the plan how it coordinates with Medicare before declining Part B; Medicare.gov’s who-pays-first tool treats ALS separately. In Texas, people under 65 with ALS also have guaranteed issue Medigap rights for six months starting the first month of Part B.