We really need the OP to come back on here and clarify a few things. Did the biologist recommend stocking that quantity of 3" fish to take predation of stocked fish into account? Why did they specify 3" fish and not 2" fish? Too many unanswered questions to keep making assumptions.
If the goal is to stock 3" fish, AND you had 50K fish in the pond from the first hatch, then seining and stocking fish less than 3" would be detrimental to the plan that was laid out, no matter how fast the remaining fish in the pond grew. Remember, when someone says 3" fish, usually they will be roughly 2.5"-3.5" in size.
Like ewest said, using a blocking net would increase chance of survival. Stocking all at once will increase chances of survival because of the sheer number of fish stocked at once. The predators will get full tummies and stop eating allowing the rest to escape, but the blocking net will help.
Growing 100,000 3" BG would be risky for a one time stocking in a 1 ac pond. Carrying capacity is the problem. Remember all fish don't grow at the same pace, so you will have bigger and smaller ones in the pond too.