ajax threshold, make attribute selectable independently of other sel. attribute

Hi,

i got an inquiry from my customer. He has a lot of variations with 2 different attributes (model and color).
When we have the ajax threshold activated, the possible variations get preselected nicely.

Model is a dropdown, color is color items.

My customers now wants to have the model dropdown to be always selectable on all Items, independently of the other attribute selections. If the corresponding variation with color is not available the color shall be reset. Right now, non availble models due to the selected color are greyed out and cant be selected. He wants to have only all Models shown and selectable, not all colors.

is this somehow possible?

thanks and best