Yes you are correct you can search the thingiverse app for these terms, and you'll get the adult results. However the thingivrrse app was published years ago, way before Google had manual reviews before allowing apps on the store. And sure Apple did have manual reviews, but once an app is through the review it is not subjected to another review until
a. there are enough reports by users / companies that say the app is violation;
b. IMPORTANT: The app releases an update.
When an app releases an update, it CAN be reviewed by one of the Google Play or Apple employees. 3D Geeks has been trough this process several times and actually got taken down for a couple of days because it was in violation (nsfw content) and we were forced to take action on this or suffer the concequences (permanent takedown).
The reason why thingiverse is slipping through the cracks is simple; it hasn't had a major update in years. The Android app stems from the Android KitKat age.
So no, we're not baby'ing our users. However we are forced to abide by the policy we've agreed to upon publishing the app.