I just typed what the Washing instructions said…
I’ve never noticed they had washing instructions. I should go read what my armour says.
Strange that they recommend freezing, because it isn’t going to accomplish very much and is only a short term fix. But better than nothing though.
Irradiation would be the best option to kill the bacteria. You just need to have access to the equipment. 
Put them in the microwave?
Howabout juat having, say, 52 sets of 661’s and just throw 'em away after each week then go on the the next pair? 
I’m sure you could get a price break on volume. Maybe even buy enough sets to last 10 years? Shouldn’t cost more than a few thousand $$. ;)
That’s not the same kind of irradiation. A microwave would cook them and possibly melt or deform the plastic or foam.
The plastic in the 661 armour looks to be similar to the type of plastic used for milk jugs. Put a milk jug, along with some water, in the microwave and you’ll find that the milk jug will deform. You don’t want to do that to your armour.
Nuking in the microwave will kill bacteria. I nuke my kitchen sponges to kill bacteria. I just wouldn’t do the same to my armour.