How do you approach "respectfully, I disagree" conversations about diagnoses from other providers

Especially those of you who see kids diagnosed by school psychologists or assessors contracted through the district? One of my clients was diagnosed with autism for no other reason than he seemed socially awkward and struggled with implicit expectations in the classroom during observation. Like is it just me, or is that wild? All historic diagnoses were dismissed, and he did not account for complex trauma. No other indicators of autism identified... Just awkwardness...in a preadolescent with complex trauma... The family asked me about my thoughts, and honestly it was a little awkward. Normally navigating conversations like that is my jam, but that one flopped notably