You said "now have autism"? The "now" implies that they did not before, or that you at least did not know it before.

No, now means they have autism right now. It does not imply the did not have it before.

It can be interprted that way, but its a bit stilted. No worries though. English is famously confusing.

It reminds me of: "I used to do drugs... I still do, but also I used to." - Mitch Hedberg

Its funny because nobody expects you to use the language that way, but logically its still valid.