They need a booth. Why? Because they are going there so they can spare the manpower. If you are sending a personnel there to attend the conference, you have the spare personnel to man the booth.
How else are they going to work the conference? Suitcasing or outboarding?
This is the only reason why they need a booth there. There are no downside since they are going to be there. 10x10 booth cost $30,000, which is what they gave Zack over the course of a year.
If they just want to meet with investors they can do it at NC, where it won't cost him a dime. Why do it at RSA if you don't have brand recognition and new customers/leads in mind?