I think many bureaucrats everywhere view the press as an annoyance, but in places where they're used be being able to push the press around, pushing the press around becomes standard operating procedure even when there's nothing in particular to hide. Also, without a free press, nobody is incentivized short-term to dig deeper if a cursory investigation doesn't turn anything up. The end result is predictable stonewalling if a cursory investigation came up with nothing, even if the officials are pretty sure they have nothing to hide. (Also, due to incentives, it's harder for officials to be certain they really have nothing to hide.)
Having been in Hong Kong for just under a decade, I've seen several cases of bureaucrats making tone-deaf statements partly because they aren't used to dealing with a free(-ish) press. I have journalist friends, and I wish the relationship with the press were different, but bullying the press is less a sign of a cover-up when officials aren't used to dealing with a free press.