Lame Oracle Curse states "One of your legs is permanently wounded, reducing your base land speed by 10 feet if your base speed is 30 feet or more. If your base speed is less than 30 feet, your speed is reduced by 5 feet. Your speed is never reduced due to encumbrance."
The question here, if you are using a form of movement other than land speed, like flying or swimming etc. Is your speed still never reduced due to encumbrance?
That would be the case; the penalties are specific to land speed, while the benefits affect all your movement speeds.