The max Rds(on) is quoted for Vgs=5V. That means it will be on at 5V gate drive. That's the only
spec you need to look at for gate voltage. Don't be confused by the threshold voltage, its nothing
at all to do with switching on.
If a device only has an Rds(on) figure for Vgs=10V, you cannot assume anything less than 10V
is adequate.