I doubt very much that FxTec would like to mess with the OS to disable this, as their attitude has been to stay as close to stock Android as possible, only changing stuff where it relates to the Pro1 Hardware (particularly the slider functionality, as hardware keyboards are already supported in stock Android).
This is certainly not the only annoying 'feature' in Android, and as far as normal third party apps can not fix them, LineageOS or rooting might be the way to go.
Just a thought. Restricting what ever offers the sharing from accessing contacts MIGHT fix this particular issue. I