Heard this news too. I did estimate ~25% botnets/viruses and ~25% ASICs in this year beginning. As we can see since April 6, after anti-ASIC hard fork to CryptoNight variant 1, total hash rate became ~1/2 of the previous one. So, actually I did over-estimate botnets/viruses hashrate and under-estimate ASIC hash rate. Now it is evident, ASIC was THE MOST VIOLENT disaster of Monero's hashrate, ~50% of total one!
Now consider botnets/viruses. Most of them might update their mining algo since April 6, or even find new vulnerabilities to inject new mining algo. But total hashrate does not increase, furthermore it does slightly decrease since last Monero price fall at ~June 13. Note, ~2.5 months have been passed since April 6 hard fork. Enough time to improve/upgrade botnets/viruses! So, we CAN NEGLECT botnets/viruses hashrate at all. And this assertion fits with Josh Grunzweig result ~2% (of total hash rate) from the article you mentioned exactly.
From the other hand, essentially the fact that Monero CAN BE mined by viruses does confirm its superior anonymity and decentralization at once. Smart people don't run suspicious software or run them inside a virtual machine jail. Just said.
