One or two new weapons can hardly change the outcome of the war,That's his point, if Russia had a proper SEAD/DEAD capability there wouldn't still be strong air defences. As it is they've been reduced to an artillery game, and HIMARS is beating them.
You are right on the Russian air force, it has been broadly ineffective throughout this conflict, reduced to firing stand-off weapons.
HIMARS with a terminal homing capability could make life very dangerous in the Taiwan strait if China chose to invade Taiwan.
In fact, China has a large number of 300mm satellite-guided rockets in stock with a range of 145KM. If Russia needs it, it can be provided to Russia, which is much better than HIMARS.
HIMARS artillery is not new, China exports a lot of SR-5 to the UAE and Algeria, but Russia has long ignored the long-range rocket system, so it seems that HIMARS is very advanced
As for the Taiwan Strait, in fact, the solution to the problem is very simple. A large number of high-altitude balloons carrying high-performance thermal imagers can realize 24-hour monitoring of the battlefield, and then use ballistic missiles for rapid strikes, or the army's own M20 missiles.