It's different from the Taiwan scenario. Even PLA artillary force can cover the whole island using MLR. And the main base is in mainland China, no limitation of throwing in the forces.
All their air force can be wiped out in hours, all radar signal sources will be bombed out of hell.
They still can use rifles, yes but not much use.
IMHO, this is a gross exageration and simplification.
The ROC has known of the quantitative advantge of the PRC all along and has prepared accordingly. They have hardened facilities and dispersal plans which will preserve most of their air force.
In order for the PRC to invade, they will require total air and sea dominance, otherwise, their ships full of troops will be at great risk, as would any invasion plans. I believe the ROC Air Force and Navy would hold out not only for days, but probably for weeks...even if the island was being hurt badly by the missile barrages.
With the US stationing more aircraft in Guam and the western Pacific, including Raptor F-22s, and with a second aircraft carrier being deployed there, the US would have very effective fighter cover over the island to assist the ROCAF within a few hours, and significant carrier cover to the east of the island within a couple of days. The fact that the US is moving more and more of these forces (including numerous nuclear attack submarines) into the area is a signal that the US takes the threat seriously and will be willing to respond to it.
I pray we never have to find out.