I use a bd-1 and the seat moves everytime I fold is enterely.
Putting a center spot at the right height helped to put it back at the exact same position everytime, just within a few seconds, so it's a fairly solvable issue.
Now I'd hate to fiddle with the frame every time I park, but I guess people have different tastes.
Either this, or mount it ungreased. I guess in both cases this bike will start to creak much earlier than a regular one. If you grease it and keep it outside of the seat tube, a lot of dirt will stick to it which then makes its way into the seat tube. When it rains more water then usual getting in the bottom bracket area will be another challenge.
Seat posts, especially of a different metal to the frame (e.g., carbon or alu seatpost in a steel frame), regularly seize in place without grease (from galling or corrosion). Often in a matter of months. I’m amazed you’ve never run into this or heard of the idea in 15 years of professional cycling. Did you ever work on your own bikes?
If you’re looking for more friction than grease, you can use carbon assembly paste. But either way, you want something between post and tube.
Putting a center spot at the right height helped to put it back at the exact same position everytime, just within a few seconds, so it's a fairly solvable issue.
Now I'd hate to fiddle with the frame every time I park, but I guess people have different tastes.