What does a building with 10 emergency exists, lots of individually lockable suites and rooms have to do with guns?
Santa Barbara has strict anti-gun laws already. CA has a lot of anti-gun laws already. The UCSB system has anti gun laws already.
Santa Barbara issues something like 50 permits a DECADE for concealed carry. It's a "may" issue jurisdiction, and they don't issue.
And if metal detectors are implemented, I'm not sure students will care. They already exist for large sporting events and other areas of concern, so if there was a concern you'd want fewer main entrances so you could staff them.
Bigger issue is normally non-students in student housing, so security can be good in terms of setup. This means the newer buildings often do things like keycard access to suites only for suite holders, and some even do keycards for your room separate from suite, again, all logged and tracked. I visited a friend at a school where I had to sign in my car with a guard, had to be escorted to their room by a front desk staffer etc. That's extreme - no way UC is going that (this was a small elite place).
The major student issues in terms of safety are stranger access to dorms / bathrooms at night, theft issues (bikes / bags etc), and nuisance issues (noise, weed smoke, parties etc).