If their "professional ethics" prevented from taking part in the execution, why did they wait for "the last minute"? Shouldn't they have declined much earlier? This sounds like a political stunt to delay those executions.
That is exactly what it was.
"The two unidentified anesthesiologists involved in the Morales case issued a statement after withdrawing from the impending execution, indicating that they had not initially envisioned playing a role in the administration of the lethal drugs the state uses to put inmates to death. However, after examining a Feb. 20 opinion of the Ninth Circuit Court of Appeals, it became clear to them that they might be called on to intervene "if any evidence of either pain or a return to consciousness arose.''
In other words, if for some reason Morales did not die as expected, they would be called on to order more drugs. "Any such intervention would clearly be medically unethical,'' they wrote in their statement."