Well, if you look at the AV industry at a broader view, you can see that the current situation can roughly be characterized like this: there are small players that keep taking considerable market shares, reducing the market shares of traditional giants like Symantec and McAfee. Of course, I'm talking about small players like AVG, ALWIL/avast and Avira (all offering free products, essentially).
Now, the big players are not blind, and especially the investors standing behind these big companies are not very happy. Particularly in Europe, the situation is quite serious, with AVG in the UK (~35% consumer market share), avast in France (~45% consumer market share) and Avira in Germany (~52% consumer market share).
Now, Symantec had a couple of possibilities of how to cope with the new situation. One of them was to start offering Norton Antivirus for free, but that wouldn't be too wise as it could hurt the value of the Norton brand (still considered by the company as "premium").
A better way to solve the problem was to launch a new "budget" brand - offering cheap (or even free) solutions under a new brand, but still under the wings of Symantec, regaining the lost market shares. They could either develop the products themselves, or, more easily, acquire another well-established smaller company that would give them what they need.
And I think PC Tools is going to serve exactly this purpose.
Cheers
Vlk