Yes, that's true but I, like many regular users, find a scanner without cleaning ability to be kind of useless in the commonplace context.
In order to clean malware, you have to find it first. Cleaning can be done manually pretty easily, but detecting it, not really, even if you know, what to look for.
I'm interested in this. Having used Bitdefender in past (the paid but it is bulky and chatty), you are saying it is worthwhile to install this full AV for the ability to update its scanner? There would be no other activity on Bitdefender's part, network or otherwise even though real time is off (you hope)?
It was pretty commonly recommended in the past by AV experts, even using multiple realtime AVs at the same time. These days, when AVs are more compatible than ever, it is discouraged. If you install AV and disable realtime, auto-updating is in place including shell for scanning, sure it can be done with some on-demand scanners, but why bother to do it manually, it is too complicated. In order to update most on-demand scanners, you have to run them first or even re-download, like Cureit, KAV.
P.S. WD works the same way, all its services are up and running, just the realtime is disabled and everyone is excited about it as if it is some cool new feature.