The short answer is yes. This is accomplished either during the recording process (PowerPoint has a Camtasia plugin to record everything) or after the fact by importing audio and slides as graphics.
Some pros and cons of recording the PowerPoint: You would preserve the presentation timing (for better or worse) and any native PPT transitions used in your show. You're also stuck with it in some sense as it's less flexible.
On the other hand, I recently had a 5 minute scripted audio narration ready but the PPT slides were not quite finalized. Once those were selected, I used Snag It to make a PNG (or JPG) graphic file for each slide. I didn't use any PPT animations so nothing lost there.
Once they were all in the clip bin, all I had to do was drop them on the timeline and stretch them to fit each narration topic mentioned. Then I used some Camtasia transitions and effects to improve the show or at least make it more interesting.
From there it was render and share as usual. Heat and Serve!
Thanks for including the end game, I can understand your goal. I imagine the SMEs are largely unscripted and that Camtasia could be used to tighten up the shows for your distribution from LMS.
Camtasia can import many types of audio, video, graphics as well as Camtasia specific assets. It cannot import a Powerpoint presentation file natively, it doesn't know what it is. So that is why the PPT plugin allows Camtasia to record the presentation in a format that it can recognize.
Here's something you might try; this article talks about saving a PPT as a video "WMV" file that could then in turn be opened in Camtasia for editing. https://support.office.com/en-us/article/Record-a-slide-show-with-narration-ink-and-slide-timings-3d...