BrokenEchelon
Banned
There's no reason to believe Varys and Illyrio have any inkling of Jon's heritage or significance. Varys doesn't seem to be the type to hire expensive magical assassins either.
Do you have a theory about it?
The only person left alive who would know about Jon's supposed heritage is Howland Reed, and it seems doubtful that he would have any reason to be involved in such a plot, or inform others who might be involved in it.
Varys on the other hand was present at King's Landing during Aerys II's rule and he spoke out against Rhaegar to Aerys regarding the Tourney at Harrenhal.
Rhaegar also did send three of the King's Guard to watch over Lyanna at the Tower of Joy, something I'm sure Varys would've been aware of and curious about.
Correct me if I'm wrong as it's pretty late and I'm tired.