This has to do with how computers store numbers. I believe internally C2 uses a range of 0 to 1 for opacity, but has to convert the value to the 0 to 100 range. This leads to inaccuracies. You'll see many forum posts about checking exact numbers. It's generally best to assume a small range. Checking round(timeTravelable.Opacity) = 70 will also work.
If you log the values of opacity in the Console, you see that the opacity in question is actually 69.999999, where as the other is 50.
The joy of computer math!