In my opinion it could be a number of things.
1. He could just be startled every time you open up the cage
2. Could be husbandry related issue causing the snake to be stressed out all the time. Make sure temps and humidity are proper, etc.
3. Maybe you have a scent of a predator? have a cat maybe? lol
4. The fact that you even think about him striking or are concerned about it means there is some level of hesitation in you and while holding the snake it can indeed sense this and will stress him out. When you go to handle the snake dont even hesitate, dont show any fear, just pure calmness even when the snake seems defensive. It'l eventually sense that you're cool and it'l probably be more relaxed.
5. Could just be near shed?
6. Or its just his attitude plain and simple. Some snakes are just like that and some grow out of it with constant handling but older ones dont unfortunately.
At your pic though. That does not look like strike position, strike position the snake would be elevated a bit. Looks more like cautious there. Not scared though, it would have balled up if that was the case lol.
I say dont worry about it too much. If the snake is eating and shedding fine and no signs of any injury or RI then he/she is probably just fine.