Greater/ normal Arson causes you to not be able to manipulate your build, that's what you were missing - nados would similarly be affected. We do not want land taken from in progress unless its because there is nowhere else to take it from. That is the current behaviour and we don't intend on changing it. You can, ofc, argue as to why you would like it changed but be aware that its just not something we are interested in changing right now.