If that's the problem, then shouldn't they explain the connection? Since they won't, it's only natural to assume the obvious.
And why would one presume them utilitarians?
The guys at Dropbox are smart; isn't the "obvious" assumption that Rice could be useful in helping them to better manage some of these interests (e.g. potentially reducing govt. snooping by facilitating a more level playing field for comms. and negotiation)?.
Aren't most reasonable people utilitarians? :)
If by reasonable, you mean "rational" in the sense of rational choice theory, and if by "utilitarians" you mean "maximize of their own individual utility" rather than "adherents to the philosophical school of utilitarianism", then, yes, all reasonable people are utilitarians, by definition.
As for character, it's unclear what's unsettling about presumed utilitarians acting towards what they believe to be best outcomes.