Apaprently you did not read the studies you posted. At least the first one since it contradicts what you claimed based on the study. You said:
" It also seems to have the ability to grow with age, suggesting elasticity and further suggesting it can be dilated to pass stones on its own over time."
Yet the study you linked (http://radiology.rsnajnls.org/cgi/content/full/221/2/411) states:
"CONCLUSION: Findings were not able to help confirm an association between age and size of the extrahepatic bile duct in an asymptomatic adult population."
Note that they said the finding WERE NOT able to help confirm the association.
In the second study you linked they state "there is a mild change of duct size with age." Mild change? That could be so minimal that it still defeats your conclusion. Not to mention that a slight increase should be expected due to loss of elastin with age. The same reason that non-exercise induced varicose veins are more common as we age. The loss of elastin will cause such tissues to stretch out slightly, but this due to loss of elasticity, not increases in elasticity.