Winterize - Put Pink Stuff in Pump Only?

The problem in not putting antifreeze into all of the pipes is the possibility of fresh water collecting in any low spots. Unless you use artificially dried air and pump enough air to evaporate all of the water out of the pipes there is always a chance that what was originally a thin film of water may drain over a period of time into the low spots and freeze. Once the pipes are no longer filled with water, the air can blow over the top of water collecting in low spots.  Then the air has to have enough velocity to create large enough waves for the air to blast that water farther down the pipes.
Ice has the character of expanding in all directions not just along the pipe. If there is little water to collect, there won't be enough ice to crack the pipes.
If you are a gambler...air blowing the pipes probably will remove enough water to prevent pipe breaking.
Many of us just don't want to hazard the bet by just air blowing out the water.  Most of the Pods take less than two gallons of antifreeze, which is a small price to pay.  If you didn't adequately blow out the pipes, your repair costs are going to be many times the price of the antifreeze.