My interpretation is that they not calling this a bug or a flaw, but a logical consequence of the design, and does not represent a flaw because the original specification didn't specify the implementation be resistant to this kind of attack.
A bug would occur in the case where the specification specified that there were no visible side effects from these mispredicted speculative executions, and the processor implementor failed to implement that part of the specification. This is a big deal because if it's a bug, Intel is liable.
It's likely all processors with these kinds of features, the specs will get updated to be more specific about these kinds of side effects.
The KRACK attack from a couple months ago it's due to the fact the WPA2 specification was ambiguous about what values to accept. Most implementations allowed decrypting traffic and a few even hosts impersonating other hosts but they were perfectly conformant. I would say there is a flaw in the WPA2 specification.
There are always going to be unintended consequences but this one about effects of branch prediction seems, ironically, quite predictable.
That's a philosophical stance known as "positivism."
Who do you think wrote the spec here?
It's a huge lapse in customer trust, for sure. But if you're just going to play that semantics game...
I think the good point here is whether or not Intel engineers knew of patterns like this (they should have) and is it negligent or unethical to release products that have these vulnerabilities built in. Insecure (or "undefined") by intention or by coercion.