I must disagree. Toolset does not come last or first. It comes together with other important considerations about home defense. My point of view is supported by POST 2 in the thread the OP referenced.
https://www.thehighroad.org/index.php?threads/home-defense-toolset-comes-last.870825/
Written by a LEO with 26 years of experience we read an informed point of view based upon experience. I happen to agree with everything he wrote even though my experience in clearing rooms, etc was limited to two weeks in Hue City. I slung the M16 across my back because I the M1911 I carried to be better suited to extreme close quarter gunfighting. Others will disagree with my choice.
Getting back to my point no matter how much defensive preplanning you do, and it is important to do it, weapon capability and suitability are just as important neither is first or last. They go together. Consider this analogy. You want to build a small cabin but never have built much of anything. How do you plan to build the cabin if you do not know what specific tools are needed and whether you are capable of using them effectively not theoretically.
There is a reason I carry my LCP2 on my person in the house all day and night long until I retire when my bedside gun becomes my primary. The reason is simple. Referring to the LEO’s Post mentioned above you just do not know where the danger will come and when. My choice of a carry pistol all the time means no matter when or where an attack comes from Imam prepare. The only way I can duplicate that with a long gun is to carry the long bun all the time. Really, I do not want a rifle next to me when I cook, dine, watch TV, etc. I am not going to stash guns all around the house because going to retrieve a gun under sudden attack is not a efficient as having a gun on your person.
I have a home SD plan. You can see my preparations in post 10 at this link:
https://www.thehighroad.org/index.php?threads/unfortunate-armed-burglary.870203/#post-11539285
The longest shot I would have to make is 25 feet from my loft to my doors. A pistol, even my LCP2 more than suffices. And unencumbered by a long gun I could retreat to my loft much faster and agile than with one.
So for me the process of selecting a home SD gun was based upon suitability for CQ gunfighting along with an understanding that my choice would be sufficient. That is why I thing it is all one step not two.