Sorry but this whole situation is making me cross with the setting.
This is a little boy who is just 3. Almost his whole life has been in lockdowns so he hasn't had the same opportunities for socialisation as children his age pre covid, or children his age who attended a setting as keyworker children, for example. On top of that he has been 2 weeks in this setting. 2 weeks!
In addition, they are extrapolating from very little. Lining up items is not in itself a red flag for autism. It's part of typical toddler play schema. It would be a concern if all his play involved organisation of items, or if he became excessively distressed if someone (adult) joins his play, tries to develop it, or interferes with the schema (eg adding an extra duck to the end).
I was going to suggest you consider selective mutism, but he wouldn't even meet criteria for that if he's only been in setting 2 weeks. It's not unusual for children to need a good half a term to settle in, especially so post covid.
So, cutting a long story short, I don't think this setting has a reasonable understanding of child development or any insight into children post covid, and that makes me dubious of its "best in the area" status. Do you mean highest scores in SATS? Because to be honest if you have a child inclined to anxiety, a setting that is more child focused, nurturing, and less pacy and academically focused might well be a better fit.
25 years in educational psychology in case you are wondering my credentials.