This is correct. The problem was that there are requirements on those plots that are supposed to stop people from being able to place them if they don't have the Creation Club stuff. There were two ways that was being bypassed that were giving people crashes. The first method was via "unlock all building plans" - which was making them available for construction even if people don't have the content and then they would build it anyway (ignoring the warning in the plot description). Second source was city plans, which would effectively also unlock and bypass the requirements. By all indications I think most city planners assumed that it would substitute something else if they didn't have the content, but it wasn't doing that because the code didn't know it wasn't supposed to be letting players build those. There was a fix in the core SS2 mod made where you can set building plans so it always observes the requirements no matter what, even in the face of unlock all building plans or city plans. I forwarded that into Jampads so now it should never happen again (hopefully - I've tested it many times successfully having creation club content installed and not installed, but you never know!)