I wouldn't attribute this to malice when it can also be explained by incompetence.
Sonnet 3.5 New > Opus 3 > Sonnet 3.5 is generally how they stack up against each other when looking at the total benchmarks.
"Sonnet 3.5 New" has just been announced, and they likely just haven't updated the marketing copy across the whole page yet, and maybe also haven't figured out how to graple with the fact that their new Sonnet model was ready faster than their next Opus model.
At the same time I think they want to keep their options open to either:
A) drop a Opus 3.5 soon that will bring the logic back in order again
B) potentially phase out Opus, and instead introduce new branding for what they called a "reasoning model" like OpenAI did with o1(-preview)