'They were also told not to “provide any opinion,” according to a copy of the email',
is the part that I take as the directive not to say anything contradicting Trump.
it further reads "One of the things we train on is to dispel inaccurate rumors", this is where he feels hampered to dispel the rumor caused by Trump.
The part with the 5-20 percent in full is
"The official said the statement called out Birmingham’s tweet because one NOAA hurricane forecast product showed a 5 to 20 percent chance of tropical-storm-force winds in a small part of Alabama.
“It was nothing against Birmingham, we needed to make sure forecast products reflect probabilistic guidance,” the official said, referencing the extremely low odds for tropical storm-force winds.
Such wind speeds, between 39 and 74 mph, rarely cause much damage or require the advance preparation.
The NOAA statement made no reference of the fact that when Trump tweeted that Alabama was at risk, the state was not in the National Hurricane Center’s “cone of uncertainty,” which forecasters use to determine where the storm is most likely to hit. Alabama also had not appeared in the cone in the days before that."
So to me, that says the small percent that is being used to verify the president's claim is insignificant.
This doesn't mean that I don't get your point. You're saying that the article is exaggerating the pressure on the NOAA.
That is also why it would be nice to see the whole emails first hand and not rely on the article.