They don’t need the subs to take out the supertankers. Simple sea mines would be more cost effective. As such, best use of the Kilos might be as undersea minelayers. Sew a minefield across the strait & ‘declare the strait closed’.
I expect that the Iranians understand that the Kilo’s would be ‘toast’ once this happens, so they’ll push them out into the Indian Ocean to hunt the carriers. They probably won’t survive long due to crew proficiency, but the fear-factor to the US CVBG’s would be disproportionate.
We do have anti-mine capabilities, and we can use other sonar devices to detect such chokepoints. Tankers might move through their more slowly, waiting for an escort, but they'd still get through the strait.