Depending on your genetics, you might be able to get away with it. Either way, I don't know why your having a low protein bar, unless your gonna have a protein shake or can of tuna with it?
I'm not familiar with the particular bar your refering too, but generally those bars are so easy to eat. I know they may have some fiber in it, but in my opinion its still evil. For optimal results I think its better to just eat 19 grams of carbs from oats(or most vegetables and fruits) versus that bar. Though, you still may be able to get away with eating those bars and staying lean. I think one problem is, for me at least, when I eat a bar like that I want to eat more and more, but if I eat oats I feel full with a lower amount of calories. What I mean is 200 calories of oats should make you feel fuller than 200 grams calories of bread or granola bars, at least it does for me.