And before we hear the typical Tom Clancy-esq fantasy fiction about US subs' invincibility and suggestions that they covertly entered Chinese waters to get the 'money shot', one should consider real world concerns.
Firstly, the PLAN decide when and where they send their attack subs. If they were seriously concerned that USN subs might be sneaking into Chinese waters for a peek, it would be easy for them to set up a welcoming committee with their SSKs waiting and a nuke sub acting as bait.
This is not like sneaking a SEAL team ashore where no-one is looking. This is running the teeth of the PLAN's ASW gauntlet where the PLAN decide, and when they decide.
Consider the real world consequences if a USN nuke sub was caught inside Chinese waters. That sub and its crew will be impounded or destroyed if they tried to flee. The US would be forced to make a formal apology if it wants the crew or sub back. It will be a massive black eye for the US politically and militarily either way, as the Chinese will probably plunder the sub's secrets and send it back to the US in pieces if they send it back at all.
The consequences are so grave I seriously doubt the US would risk it, no matter how confident they felt about their odds.
That is probably also why the US bothers to send monitoring ships so close to Chinese waters, and also why the Chinese get so annoyed when they do get that close.
Have you also considered that this could be deliberate misinformation released by the USN to mask how much they truly know about the PLAN's capabilities?IMO, the reason that they gave type 095 its "noise rating" is due to the fact that they saw type 093 evolution compared to type 091, made some assumptions, and after that made an estimation. They know that china has a big gap, and dont have reason to believe that china can bridge it anytime soon. Not without massive transfers of russian SSN tech.
Bare in mind that everyone involved in the drafting will know that the report would ultimately be released and made public. It is entirely possible that the USN would want to trick the PLAN into thinking they had a worse idea than they actually did. Maybe to tempt the PLAN to be more advanturous with their new SSNs and maybe actually expose them enough so that a USN sub could get a good signature.
When you consider that PLAN SSKs are widely accepted to be just as good, if not much better than the Kilos they bought off the Russians, which itself is recognized as a very capable sub, you realize that there is very little reason why Chinese nuke subs should be so much worse.
The only difference is the power plant. It is possible that Chinese nuclear reactors are not very quiet, but that would be the only bottleneck if there was one. As soon as they get the reactor noise level down, the rest of the sub should benefit from the same kind of technology as that which makes their SSKs so quiet.
That is a breakthrough that could be made at any moment, especially when you read about all the advancements China has made in its civilian nuclear reactor field.
That is why Chinese tech levels tend to jump so quickly compared to the speed those technologies were pioneered.
Unlike the pioneers, the Chinese have a pretty clear idea of what they need to do and how to get there, and it is often only a few key bottlenecks that are holding them back.
They may really be at 80s level of noise signature now, but as soon as they cracked the bottleneck, they might jump instantly to 2000s levels in a few short years or months, just like how they are with turbofan engine technology, radar technology, hell, every major technology you can name.
The report you cited seemed to think that it will take the Chinese just as long to play catch up as it took to pioneer the tech in the first place.
That is another obvious logical fallacy, and together with the obvious factual errors, casts serious doubts as to the relability of the report and the validity of its conclusions.