I don't have a dog in this race, but the statement was that Google abhors patent trolls, not patents. If they're buying up patents with the intent to use them to build something rather than flip them, that is not inconsistent.
Patents and patent trolls affect different-sized companies differently and can be competitive advantages for large and incumbent companies as barriers to entry for new companies. Bill Gates knew his competition would come from two guys in a garage (or graduate school) more than another big company, so his company would be enthusiastic about such barriers.
Here's how the barrier works against potential new entrants.
Large companies with large patent portfolios mutually license portfolios in exchange for not suing each other, giving them competitive advantages over small and new companies. A new company with one legally defensible patent can't use it to compete with Microsoft, who will claim the new company is infringing on several of Microsoft's thousands, or the mutually licensed ones with other companies. Any non-trivial code can reasonably be claimed to infringe on some patents. Even if it isn't, no small or new company will beat Microsoft.
What about trolls who don't intend to bring a product to market and just want money?
Large companies with large legal departments can defeat most patent trolls with experience and having large budgets. Paying all the lawyers may cost them money and they'll lose some, but money and experience will win most of the time. The point is it creates another barrier to entry to small companies with fewer resources to fight back. They either have to give up or pay the troll, losing profitability and ability to compete.
So patent trolls still create a competitive advantage for Microsoft. Microsoft's legal costs may decrease its margins, but they remain better entrenched, improving stability and profitability overall.
Why wouldn't Google like patent trolls?
Google's profitability doesn't depend on selling software nearly as much as Microsoft. It profits from advertising. Software patents give them advantages over small and new companies, but not as much as for Microsoft. Take away software patents (how else to get rid of trolls?) and Microsoft will be reverse engineered away. Google will continue.
The statement isn't nuts if Microsoft intends to play patent troll themselves, which they have done against Android. They have at various times gotten a fraction of smartphone sales running certain versions of Androids because they hold the patents on various trivial design decisions and algorithms.
