We Know He is Alive!

The people you mention were briefed by a hologram of 'the old man'. Everyone on board knew who Weyland was.

That's right Savage. Obviously David, Vickers, and the medical team knew Weyland was onboard however the scientific team was probably kept in the dark - no reason for them to know until they "met their makers".

It seem to me that Shaw and Holloway were deliberately kept in the dark about Weland's presence. He did; after all, sort of usurp (by funding) their discovery in order to profit by way of extending his own life. Simply put, Weyland's motive was different than Shaw's. Vickers did state in the film that Weyland wanted a "True Believer" on board the ship- in addition to the other crew. But their motive was secondary at best to Weyland's.

I wonder if Holloway was kept in the dark..after the initial meeting of Vickers/Shaw/Holloway? Vickers might have anticipatred the problems with Shaw,being believer. That implies that Holloway was not a believer. Vickers seeing this might have pulled Holloway aside(using whatever enticements that would wotk with him)and inform him of Weyland being on board. This would give Vickers not only additional influence over Shaw,,but an additional; source of info. By having Vickers/Holloway aligned gives a better explanation of the Holloway sacrifice scene. Hollowway realized that Vickers and Weyland will not even try to help him and is forced to stay outside the Prometheus. Shaw at least wants to try to help him..his true love. So to pay for his sins he is willing to sacrifice himself to show the other crew members how wicked the Vickers/Weyland Corp is..not being even wanting to help a sick employee. Being heartless Vickers needs to protect the Company assets and seems horrified not because Holloway was dying,,but becuase she now has her hands dirty in the act,,cerainly the first time someone forced her hand in such a deadly manner.