"Crossflo does not appear to be the primary focus for generating revenue as stated on the company website. Why the retention bonus for another failed M&A?"

Because there is no way they could sell crossflo without the software engineers still onboard? I also believe that they were trying to make an upgrade to the software to make it more user friendly. Still in any case those engineers are a necessary part of the package. The alternative would be for the customer to call Gloria, or the janitor. I'd pick the janitor.