Can you please post a link to high quality images of your own fingerprints? It should be fine, probably nobody has the technology to make them show up on a threatening letter mailed to the government, or anything like that.
Of course I won't, but then again I would send you pictures of any other body parts the same.
If someone gets a hand on anything you touched, they have your fingerprint. Last time you traveled to another country - did you have to give them fingerprints? Is the software running your phone closed source? Could you ambush me at night near my house and forcefully take them?
All I am saying is they are so weak as a secret that rhey should not be regarded as one.