It's a shame Tusa doesn't stick to what he knows.....that article is littered with duff info.
The difference between a Mk41 tactical length launcher and a strike length launcher is about 3ft, less than half what he claims. Worse still, it isn't an impact on draft (which is weight-dependent), the actual effect if any is on depth (a different parameter). Increasing depth can actually be weight-neutral, as you tend to get more strength out of a deeper section, so need proportionally thinner steel - up to a point of course!
His estimates for additional weight incurred by "plugs" for Chinook flight decks and modular spaces are also off by some margin. The average weight (not displacement, but actual material) per metre length of a T26 is about 40te/m.
The escort displacements quoted in his little table are also all over the place - there a significant element of comparing apples with wheelbraces going on in that lot.
Worst of all it perpetuates (perhaps at someone's behest?) the idea that size is directly proportional to cost. It isn't. It does have an effect, but it's far from scalable. The European warship cost rates he suggests must have been from a very small sample - as I'm struggling to identify more than a couple of "ASW" ships built in the last twenty years - let alone work out where their cost info came from and on what basis........
Warship cost is all about manhours and materials, which don't scale in direct proportion to displacement - particularly where you have effects like HV electrical systems, modular cabins, productivity / build advances over 20-odd years of nominal improvement sprinkled among the data. There are elements that add cost (additional safety requirements and procedures, software and soforth), but these are offset by use of MOTS/COTS equipments and procedures.
The question to ask is where the additional costs in material and labour are coming from - and more pertinently whether they are "real" or "programmed".