You right spotted the problem I already recognized this morning after I looked at the example code. I have to look in the code. Right now It is not possible (EDIT:) not doablebut certainly It is doable.
But another way is perhaps to find a way to query the css selector by placing a callback on the destination table, send the selector name to Node-RED and modify the configuration of the source table with an ui_control message.
It would try the tableBuilding or tableBuild callback and place a debugger; statement there. Then inspect the this.table object and lookout for the selector. Then use this.send as described to send the data to Node-RED.
Look at the copy past example how to install / use a callback.
This is the selector of one of my tables: #ui_table-8137. I expect the id is given by the dashboard and therefore not changeable. So I would go the callback route.