Jupiter's Moon Europa May Have Enough Oxygen For Life

Maybe, but not necessarily.

The heat on Europa would not come from the sun but from the gravitational friction (tidal flexing) caused by Jupiter. This would likely cause quite a bit of volcanic activity under the surface and possibly create deep underwater vents. There is an analogue on earth in the deep ocean and the so-called hydrothermal vents. There are ecosystems down there that exist without energy from the sun.

As we've discovered in the last few decades, life in general has no concept of "too cold" or "too hot," or even "too irradiated."

The range of temperatures over which water is a liquid (assuming reasonable pressures) is well within the range of temperatures that sustain life on this planet.