the purported launch,
Purported? That would be a case or maybe it did, maybe it didn't if you don't trust the source while waiting for independent verification. But wait, how does that sentence continue? Ah yes, there it is, right in the same sentence, which was verified independently by telemetry. I guess that means it's no longer a "purported" launch, what with that trusted verification and all and is now an actual launch. </snark>
Now, I suppose, theoretically, the word "purported" could relate to how the rocket was fuelled, since the US military telemetry reading probably can't identify the fuel composition with any degree of certainty, but the if that is what the author intended, he didn't do a good job of making that clear.
Sorry, not sorry, but I'm seeing more and more of this weird wordiness making statements self-contradicting these days. I didn't expect to see it in El Reg.