Yeah, it could hinder your progress on pistols. But keep in mind that pistols have a very large skill and mobility component (aside from the strength necessary). My favorite progressions for the pistol are to use a wall or doorframe to assist yourself with your hands, doing single leg wall sits, and holding the bottom position of the pistol for time. You should be able to work on these. You should also work on your stretching, as you need reasonable hip mobility and hamstring flexibility to do pistols, and this should be beneficial for your half marathon training as well.