All this appears to be looking at the impact itself, as though there was nothing more to it. I believe there was quite a lot more to it.

Debris raining down on the planet, likely ejected from the asteroid at some time, though still following in its path. The smaller craters would be more difficult to find that the serendipitous event that surveyed the Chicxulub event.

Then there is the primary's impact itself. Due to tectonic shift, it is theorized that the Indian plate was still traveling north from the Antarctic region at the time, and just happened to be opposite the impactor. The concentric coalescence of the shock ring as it traveled around the globe resulted in an upheaval that accounts for a group of ancient volcanoes in that nation, called the Deccan Traps of India.

One volcano, by the name of Pinatubo in the Philippines, has been blamed for a drop in temperature of a full degree F from 1991 through 1992. SO2 (sulfur dioxide) combines with water, forming aerosols that reflect some of the incoming sunlight back out to space. Pinatubo was a particularly nasty event, but it was also a measured event. By comparison, Mount St Helen was very clean.

While SO2 levels in connection with India’s Deccan Traps are at the moment unknown to me, sulfur is a common volcanic exhaust, and other elemental gasses could be as effective. This in mind, combining the possibility with the number of volcanic peaks in the Deccan Traps, and with that the smelted debris scattered by the primary and its entourage seemed a good idea. I can see this giving us a better estimate of the potential force involved.

BTW, unlike the revered Kevin Pope of Geo Eco Arc Research, I handled the above ciphering without a license,
Dan