Drew, I avoided the topic because I would encourage the family to see what the child is able to do before assuming that an IEP is needed. A first step, however, might be to go to a developmental center or a school district that conducts preschool screenings. All school districts have a childfind obligation, to identify students with disabilities who are at least three years old.
Though we want to see children with delays get help at as early an age as possible, I would want the parent to ask where the delays are apparent. If the boy has communication delays in particular, and possibly social/emotional, adaptive behavior, or motor delays, I would agree with you and would want to have the boy assessed to determine preschool special education eligibility. My own opinion is that developing communication skills at a young age is particularly important, as the ability to use spoken language precedes the ability to read and write.
For some disabled students, though, an IEP can be a real drawback. Special education continues to operate on a deficit model -- as there are delays we attempt to remediate those areas of weakness. The result is ongoing focus on what students cannot do as opposed to what they can. I hope the parent asks when he is school age, in a six hour day, if too much focus on remediation might actually set him back. The history of placing kids in special education programs has led to a lot of mediocre placements, or worse.
As a result, for my son, I make sure he is in a regular classroom as long as possible. He has an IEP only to aid with handwriting, as that is the only weakness he has that impairs his ability to function in a regular classroom substantially. I have no doubt that any additional services on his IEP would lead to a less beneficial education for him. That conclusion was based on what I know from experience in working with special education students, and in particular on what I know about my own son. I would hope this parent would similarly base any judgments about the need for an IEP on what the boy is actually able to do, and avoids making the assumption that an IEP is necessary because a diagnosis of autism was provided.
Michael W. Kirlin