Even if you assumed that the 12 non-founder employees equally split 50% of the company (which is almost certainly high), likely none would net $1 million after exercising their options and paying taxes. What's worse: the vast majority of this deal was paid for in stock. The Marin Software stock chart over the past two years is not very inspiring, which is especially interesting given how good the market has been to so many other tech/software companies. In an all or mostly stock deal involving a public company, you are ideally acquired by a company with a rich valuation. That's not the case here.
The $2.7 million in equity retention grants, if split equally amongst 12 employees, adds $225,000 for each, but that too is stock and the employees have to stick around and work for it. I don't know much about the acquirer, but working for stock that has for some reason languished during one of the most impressive bull markets in history isn't a very compelling proposition.
This all seems lost on the founder of the company. I can't help but wonder if it's lost on the employees too.