Instead of sharing your fears that he might be autistic (which could scare any mom into denial and anger), maybe ask her how she thinks he's doing with his development. If she's concerned at all, you could gently tell her that someone you met online told you that you can have a child screened for any delays or problems at the health department for free.
It doesn't matter if she does or doesn't have health insurance or even is as rich as Bill Gates, they will do a screening on any child three or under for free. (Three or older need to go through the school district.) Having had both of my daughters screened and found to have serious speech delays I am very grateful for the screening. Especially since, with therapy, they are quickly catching up to where they need to be.
If it is autism, the screening is still the place to start as it is how you begin the process of therapy and observation to eventually be referred to Children's in Seattle for diagnosis. The people she meets will be able to tactfully guide her there, and you won't have to risk your friendship, but just be a listening shoulder.
Early intervention is the key for a normal or more normal life for any delayed child, but if she won't seek evaluation, there is nothing you can do.. tread lightly and if all comes to worse, the school district will pick up on it when he is a bit older.