How to default logic high after a voltage divider?
There is no universal answer, since the strength of the pullup depends on the current from the high voltage side. That's why a diode translator is more effective:







simulate this circuit &ndash; Schematic created using CircuitLab

A low on the input pulls the output down to Vf. A high on the input 
is blocked by the diode, and the pullup pulls it up to 3.3V. And since there is a pullup, a floating input lets it take over to pull the output up.