... it seems silly to have both firefox and safari. perhaps there is some unificaiton strategy that we can get these two to pursue. combined, they certainly have enough marketshare to drive webmasters. --sergey This line of thought seems somewhat nefarious. I suppose you could say it was just to fight back against msie, but in retrospect it feels like a plan to dominate web development.
Charitably, his thought at the time seems to be that those two vendors could create a viable competitor to Internet Explorer. People forget how much IE dominated the browser market, and how much that hurt the web. Ultimately Google would create its own browser monopoly, but this statement does not seem to refer to that plan unless you read a lot into it.
There were a lot of cool ideas in the pipeline (particularly from Mozilla) that were dead in the water if IE didn't buy in. The modern state of the web is partially due to the fact that this kind of backroom dealing finally snapped the market out of IE's hands.
At the time of these emails, getting Apple on board with supporting modern features instead of them deciding, like Microsoft, that the web wasn't important was key to that strategy. The kind of damage Apple could have done would have been to forge their own path or to combine forces with Microsoft in the decision-making bodies about web tech.