I found an interview with director James Bobin that sheds some light on this:
With Time it’s like how he holds himself, his walk, how he sits, you
know, it being a thing whereby we’d already had a lot of English
accents. And Sacha could do pretty much anything.
And we thought time
as a concept is a kind of a Swiss idea, like clock makers etcetera. And
in Switzerland there are two languages, French and German. So we
thought German was quite precise in its language.
And then we thought, well, you can’t just do a basic, German, you
know, you have to do something fun with it. And so we thought like who
has an interesting voice who is German? And we came up with our
friend– our documentarian friend who Time is basically based upon.
This "documentarian friend" is Werner Herzog, as James Bobin confirms in this interview:
Was it Sasha Baron Cohen's or his idea to play Time as Werner Herzog?
Ha! You spotted that.
Well, Sacha and I have worked together for years creating characters, so we had a fun time doing that. When you talk slowly and precisely, even if you’re saying things that aren’t intelligent, you sound intelligent. That felt like a good thing for the character to have.