Google could have tried to do a deal to bid and be able to indemnify anyone it wanted. Microsoft might or might not have been open to bidding on those terms, but it seems Google didn't even try.
Weird indemnity clauses are fairly common in patent deals. For example, Microsoft was already indemnified against the Nortel patents, and yet bid anyway.
From what I can tell the Novell patents were not a prime motivator to light Google's ire (these are the patents Microsoft says Google did not want to purchase with them). I see no evidence or statement from Microsoft saying they offered to team up with Google (and Apple, and RIM, and various other companies) in the purchase of the Nortel patents.
They’re doing this by banding together to acquire Novell’s old patents (the “CPTN” group including Microsoft and Apple
These are the patents Microsoft is referring to.
Yes, the Nortel patents are possibly more dangerous and the prime motivation for their blog post, but Google called out Microsoft on this set of Novel patents, and one cannot blame them for responding.
Google could have tried to do a deal to bid and be able to indemnify anyone it wanted. Microsoft might or might not have been open to bidding on those terms, but it seems Google didn't even try.
Weird indemnity clauses are fairly common in patent deals. For example, Microsoft was already indemnified against the Nortel patents, and yet bid anyway.