Hi @gpcroft,
This list-view name-column auto-resizing is a hairy thing. It is standard Finder behaviour, which is implemented in the AppKit itself.
I was able to disable it in versions prior El Capitan after discussions like this:
// Annoying column view in mavericks with 1.5.5 in dual mode
// https://discussions.apple.com/thread/5499589
// Columns not resizable in dual panel mode
// Persistent Name column width in List View mode
Unfortunately the old method didn’t work under El Capitan, so I left it as is. I could try to spend some time to figure out a way how to disable it under El Capitan again.