"This card gives all other creatures you control the ability to generate spore counters and convert two of those counters into 1/1 saprolings."
Nope, unfortunately it doesn't. It just reduces the Saproling production cost of your other Thallids from three spore counters to two, so you get an Saproling every two turns per
Thallid instead of every three turns. But it doesn't grant the spore counter production ability to non-Thallids.
The idea of using defender creatures is quite cool. Have you tried focussing on creatures that have triggered abilities when they die / leave the battlefield? That's what comes in mind first when I read
Korozda Guildmage.