Cannot fault him for that, it would have been a tough decision. They would gave flown him to and fro if needed.
I can fault him for not living up to the oath he swore and the responsibilities of the job he was elected to do.
As a senator he has the responsibility to be there to represent the people who elected him and to also realize that since the election of senators came about he is a United States Senator, not a senator for Montana, or Nebraska, or any other state. He is obligated to the United States and the constitution.
He might have missed the daughter’s wedding. How many military members in battle zones, emergency responders, doctors, and others with this level of responsibility can say that a wedding is more important than responding to this threat or performing the emergency surgery that will save a life.
You take an oath of office; you fulfill and live up to that oath every single day you are in that office.