The sentences that you quoted are examples of leaks that Kevin Drum believes were in the public interest. Kevin supports these leaks because they are about what the NSA chooses to do, and are therefore necessary for public debate about US policy.
Kevin clearly distinguishes between leaking NSA behavior (as in your quote) and leaking NSA capabilities (which is in the following paragraph). The ability to decrypt certain types of encryption is the sort of technological advancement that we should expect military and intelligence agencies to make and to keep secret.
Here's the part where Kevin talks about specific Snowden leaks (about NSA capabilities) that he disagrees with:
"But the rest of it is a lot more dubious. It's
not clear to me how disclosing NSA's decryption
breakthroughs benefits the public debate much,
unlike previous disclosures that have raised
serious questions about the scope and legality of
NSA's surveillance of U.S. persons. Conversely,
it's really easy to see how disclosing them harms
U.S. efforts to keep up our surveillance on
genuine bad guys. Unlike previous rounds of
disclosures, I'm a lot less certain that this one
should have seen the light of day."