The bit you quoted doesn’t capture why the reporters are upset:

> White House journalists are outraged that a threat credible enough to force Donald Trump to escape from Air Force One using an airport catering truck wasn’t relayed to them.

Point, however...

Assume you're the Secret Service's Grand Poobah of Presidential Protection. And actually trying to do your job. How, exactly, might you tell a gaggle of reporters that the President slipped out of the baddie's crosshairs, without a huge risk of them giving the game away? This ain't 1989, when their being inside Air Force One gave you total control over their communications with the outside world. And "President is in that slow, unarmored catering truck over there" may be all the targeting info that the baddies need.

Note too that "everybody else's lives are worth less than the POTUS's life" is right in that Grand Poobah's job description. And legal duties.

My guess: What actually has the journalists pissed is that they were reporters, sitting figurative feet away from a huge secret news story...and nobody felt they were worth letting in on the secret.