“The unauthorized disclosure of information about this important and entirely legal program is reprehensible and risks important protections for the security of Americans,” Mr. Clapper said.
If the program is "entirely legal", why all the effort to hide it?
Lots of things are legal that should be hidden. When the Secretary of State writes a memo to the President about how much of a dick Vladimir Putin is, that's entirely legal... but it's not something that Putin needs to be reading.
That's not the case here, but "if it's legal it should be public" is not always a reasonable standard.
The idea is that it should be hidden because if the enemy knows the details then the enemy can adapt. There are (probably) instances where this is true; more likely those involving more specifics than this does, but in any case that's the issue at hand, whatever determinations you may make about it.
There's still the question of how we ought to negotiate such things. Over the past 70ish years we've made some cuts at it, with various outcomes...
“The unauthorized disclosure of information about this important and entirely legal program is reprehensible and risks important protections for the security of Americans,” Mr. Clapper said.
If the program is "entirely legal", why all the effort to hide it?