That's only one of the three reasons in the article: 1) Reviewer burden - LLMs can produce a deluge plausible but incorrect code which can overwhelm human reviewers. 2) Safety and Security - Many corporations depend on the JDK so stability is a high priority. 3) Copyright/IP about who owns submissions generated by AI is not settled in law.
The article also goes on to compare the JDK teams policy to GraalVM, also in Oracle which is more similar to the Linux kernel policy, where AI submissions are allowed, but the human submitter is accountable to them, which is reasonable too.
It's not unreasonable, in my opinion, for the JDK team to limit AI contributions based on their stated priorities, just like how other teams might not require those same restrictions.