Not on a mac right now, but I assume a workaround could be to feed the select node to a “Hold Value” node. Then for the output of each node going to the select node, add an “Allow Changes” node and send the output of those to the trigger/update port of the hold node. A caveat would be that if you change the value of the input that is not selected, the hold node would change to the current value of the selected input.
To maintain concurrency in the graph you might have to send the allow changes output to the select node, and then use a “Spin Off Event” node to fire the events for the hold node (but I’m not sure about this).
Alternatively you could delay the switching of the port until you changed the value in the same manner, not sure about what would be more tidy and/or efficient.