Newclimber, Not sure where you saw the "Trail Camp by 1:30" That sounds like a good time if you're day hiking and want to be back to Whitney Portal by dark.
Shri S has explained the chute icing issue very well, and if you have crampons and axe, even that isn't a big issue. Just understand that glissading can become hazardous in icy conditions. People have died on the chute (a number of years ago), but in extreme icing conditions, and they did not have any gear for the ice.
The turnaround times have often been issues for people arriving at the summit at something like 4 PM. Last year a fellow apparently thought he'd shortcut off the north side and fell to his death. Another several years ago was last seen descending the switchbacks around 6 PM, and he got lost just above Mirror Lake, missing the switchback and continued walking west, trying to downclimb in the dark, cliffed out, and fell. They found him a number of days later. Another years ago was seen in October heading for the summit near Trail Crest at 4 PM. It is guessed he was overcome by cold and darkness and was found at the base of the chute, after he fell from the Mt Muir area. All these deaths are due to darkness falling on people unfamiliar with the area.
So go, with full knowledge of what can occur, and I think you will be just fine.
