Thank you again Martin. I refer to your quotation:
“But why not kill them both in hospital? This would have strengthened the novichok claim.”
If Yulia was the poisoner then she could not have tried again even if she wanted to until she had recovered sufficiently.
However, she may have changed her mind or may be being actively prevented from attempting again by those who are currently holding her.
Of course, we do not actually know if Sergei Skripal is still alive and Yulia have only been seen once since the poisoning in the famous interview she had after she had recovered.