I've used Shoe-goo after pulling out metal shards & glass from a tire. I would like to believe it helped prevent small grit from getting into the hole making it bigger and/or puncturing the tube, but, I have no proof other than I never flatted due something getting into that exact same spot.
I think the few flats I've experienced were result of the shard passing all the way through the tire case touching the tube on the ride it was picked up on, or, on subsequent rides where I didn't inspect and pull out shards before the next ride(s) and it worked deeper until it hit the tube.