Yes, but Varys claiming to be a Targ supporter might be lost on some people because he has never shown any support thus far, people will remember how he sent word for Dany to be poisoned in Series 1. By having Illyrio, people would recognise the one person who was offering Dany and Viserys safe haven, when they were wanted felons.
Having Illyrio present, would help people acknowledge that he and Varys operate on the same page, rather than him suddenly saying "Oh, by the way, I'm actually a Targ supporter"
