Bowen having to step in, might just be a blessing in disguise. It's not as if the situation is like last season, when the team had to scramble to find a BUG among Jr.B candidates. He's had regular season experience, and proven that he is capable of playing effectively at this level. Now, he'll be getting more experience under playoff conditions, and that'll be valuable, going forward.
Brochu will graduate this season, and in all likelihood, Bowen will inherit the starter's job. Post season experience will only add to his resume, and if he takes it calmly and just goes out and plays within his capabilities, he'll be fine. He does have the advantage of the stingiest defense playing in front of him, which should make this transition easier than having a porous, inefficient group protecting him.
Plat square to the shooter, stop the initial shot, and have faith that your d-men will take care of clearing any rebounds, or covering opponents in tight. Next season he'll have this experience and that'll only provide more confidence and faith in himself. It's classic "next man up"