From the Chart Supplement it seems 1O5 is unattended for all of this requirement: Mon-Fri 10 AM to 4 PM. It's likely the service in on-demand by calling up ahead.
1O5: Unattended
SIY: Attended Sun–Fri 1600–0100Z‡
While for SIY the attended duration is 9 AM to 6 PM, the FBO may have intermittent or seasonal presence.
The Chart Supplement does not have to mention such irregularities according to IACC 8 section 3.1.5.5.4.5:
The following type data shall NOT be published in the SERVICES and REMARKS sections:
g. Temporary shortages of certain types of fuel, starting equipment, or other aircraft services;
I got the chart supplement for both airports from skyvector.com.