Came across a Steam thread that actually got me curious and thought I'd ask here. So getting access to the ship market seems to completely replace the ability to scrap ships. Since selling and scrapping are different mechanically this seems a bit odd to me. Is there a way to switch between the 2 options at will or does researching impactless sites remove the ability to scrap?

As far as I recall, the option to sell ships does replace the option to scrap them, with no way to switch between the two. The major mechanical difference would be that selling puts them on the makretplace, so I guess a toggle was not considered necessary.