I'd say it's closer to not being able to stop your own fist from hitting your own face when someone stronger than yourself is hitting you with your own arm.Not being able to stop the spear that he can manipulate in the air feels like Magneto not being able to stop a metal beam being hurled at him. If it was already attempting to come back, didn’t he just have to step to the side and catch it because it would have “Hit it’s mark”?
Hence dodging it by stepping to the side then catching like I mentioned. Why was his move to put up shields? Plus if he dodged and it had to change course, does that mean that it does not lose any force by changing direction? It seems like that’s why he was so set on throwing it straight because the direction change means some loss of force.I'd say it's closer to not being able to stop your own fist from hitting your own face when someone stronger than yourself is hitting you with your own arm.
Being able to manipulate something does not mean you also have the strength to move it at will in any and all circumstances.