I think Guard Bypass may have an error. As is, there's a Stealth 3 test, followed, if the PC isn't obvious, with a Deception 2 check to blend in. It's punishing not carrying an obvious weapon by making sneaking past guards take roughly twice as long if you're not heavily armed.
The implication is that being not -obvious should trigger the whistling stroll past security ala Deception instead of the harder sneaking check. A secondary approach, rather than an additional one.
You can see in the screenshot, if you pay careful attention to the spacing, that the optional Deception check is an alternate to the optional Combat check, not to the stealth bit.