Also it wouldn't be really hard to not develop a pattern of snorkeling or refueling making them very predictable and vulnerable targets. Nuclear boats have the advantage of disappearing when the submerge not surfacing till they return.
Question for our active/armchair naval buffs:
Having the diesel running is to be a sitting duck. The article doesn't talk about it, but wouldn't the noise of the diesel hamper the subs passive sonar and make them deaf/blind sitting duck? Helicopters use active noise suppression are there similar systems that function that could cancel the noise of the engines.
Your comment is on target— noise is the problem. The article is not well informed, or informed for the “last” war, and for lesser countries than the US. IMHO, it presupposes “cheap” alternatives that will just not do in a major conflict, which it would be with the USA.
Commented on the newer long battery super quiet electric boats— they are pretty sophisticated and scary.
Family member was lifetime submariner— pre WWII to the Nautilus and then reservist from then on until too old really. Knew everybody including the famous ones (and the nut jobs, LOL).