No doubt it's a little disappointing to have this hydraulic hose outside the BB shell if you were expecting fully concealed routing but what you have is the norm in a titanium frame. It looks like a lovely bike, I'm sure this small detail won't stop you enjoying the bike to the full!
Looks to me like SRAM Force AXS chainset, with a threaded bottom bracket shell. The crank spindle has a pretty large diameter and basically fills the whole of the bottom bracket shell. See below bottom bracket image, the plastic sleeve is nearly the same diameter as the threading. There isn't any room in the BB shell for hydraulic lines or gear cable routing.
This is how metal frames are built, the down tube, seat tube and chain stays are attached to the cylindrical bb shell which is a very standardised dimension, while BB and crank standards have developed to make maximal use of the available space.
If there is room, perhaps in a larger spec shell like T47 or some other modification, the task is still difficult and would add cost to the build with no real benefit. Some builders do offer fully internal, but they are in the minority. The hose would be forced into a tight space with very tight bends which isn't ideal and the routing would make maintenance even more of a chore.
When you have bikes with cables and hoses which pass around the crank spindle inside the frame with plenty of room, these are carbon fibre bikes where the designers have the option to create space in the frame for themthe lines to pass through.
No doubt it's a little disappointing to have this hydraulic hose outside the bb shell if you were expecting fully concealed and even gear cable routing but that would not be possible in a titanium framewith removable covers. It looks like a lovely bike, I'm sure this small detail won't stop you enjoying the bike to the full!
image sram.com