” Why did Obama say he never spoke to him”
A clinton response , similar to I was never alone . It’s so open to when he spoke, and on what , that he can issue repetitive denials , unless someone ( unlikely ) asks him:
What do you, or did you persoanly, or through any of your team, know about the filling of your prior senate seat?
You could easily followup with multiple pinning questions.
Yes, he should be asked. Will he? that’s a different question.