No, it's a problem. I agree with OP on that, just not on how to solve it. If I have lurkers aware of this privacy loophole (which also exists on LJ and simply got ported here from there, making it endlessly old and doubtlessly well-known to lurk-y types as an end result) then they know every single time I filter-post just by comparing the last-posted date on my profile with the last posted entry on my DW that's set to public viewing. That's a huge thing right there, worrying about what strangers think you just posted, to whom, why you didn't make the entry public, and so on. It can make me feel...squirmish.

It's always bothered me. Just 'til now I couldn't think of a good way to solve the privacy leak, but I think I just did come up with something (will comment below).