I always have been told once a spike always a spike. Last December I shot a deer that was probably 2 years old, weighed 137 pounds and his antlers were so small I couldnt even make a fist around them. Better to keep your gene pool good dont want them passing on bad genes. Unless antler size isnt a trait that gets passed on to the next generation. I have studied some human genetics so I just assumed antlers, as they are bone, would be passed on in their genetic code much like a tall person would pass on traits for his kids to have a higher chance of growing longer leg bones and be tall.
Lot of good info here. I too believe that a spike Buck is just a young Buck and if you want to shoot it for meat do it. If you want it to grow into a nice racked Buck then let it grow for 2-3 more years. I've never seen a spike Buck with a thick spike indicating that it was an older Buck. They all have skinny spikes that tells me they're a young Buck that will mature if you let him walk.
Not to beat the dead horse, but go with your instinct. No one's opinion should matter what deer anyone decides to kill. I know a guy who had a buck on his land with real thick long spikes for a rack. Pretty much the main beams without tines. It turned out the buck was like 6-7 years old when it was killed by a hunter that year.