Critique my Soft-start circuit
There are a large number of off-the-shelf solutions to this sort of problem. The advantage that these schemes have is not only do they manage the hot-plug, they limit the inrush current so that the power supply isn't overloaded.

Your simulation result shows a wicked slew rate after 250ms - that doesn't look at all like soft-start to me. The voltage rise should be a ramp, not a straight edge.