[Senko]

"Ewww cockroach." Stomp, stomp, stomp "Huh what are you talking about no one's been in for the past 5 hours check the camera recording . . . hey who were those guys?" as opposed to "Ewww cockroach." Stomp, stomp "yeah, yeah go on through.' stomp. "Yeah I let some scientist in he had the right access card." you mean?

[Rosa]

In my opinion the spell description supports your first example rather than the second yes.

And it's worth noting as Senko mentions, that the spell doesn't prevent cameras and other types of sensors from recording your presence and possibly alerting security.

Also I disagree with the opinion that the spell needs a higher drain code than alter memory since the actual memory manipulation in the See-Me-Not spell is far less intrusive and substantial than in alter memory.  Since the spell is supposed to be sustained, you could always discuss whether the memory loss is potentially permanent or only lasts as long as the spell is sustained.