It’s not absurd. Russia and Ukraine have been engaged in a war of attrition for quite some time now, and it’s beginning to pay dividends for Russia. Either Ukraine is running out of interceptors or Russia has significantly attrited their air defense platforms.
Having said that, Western military analysts have warned in the beginning of the year that Russia will have an opportunity this year to overwhelm Ukraine’s GBAD precisely due to an interceptor gap. However, the same people claimed that production rates for interceptors are ramping up and will surpass Russia’s missile production within a year.
You're simply assuming that Ukrainian powerplants would be more or less unassailable if Ukraine had bigger interceptor stocks, thus Ukrainian power plants being hit proves that Ukraine is running very low on interceptors.
If we don't assume that Ukrainian powerplants are more or less unassailable if Ukraine had a bigger interceptor stock, then a Ukrainian power plant being hit proves nothing.
In reality we mostly have no way of verifying either sides claim of missile interceptions, as the information vacuum is almost total with few examples of open information like when major power plants gets hit or stray videos of explosions are released.
What narratives military experts push are fairly irrelevant, they play their part in the war propaganda. Focusing on fundamental aspects like troop concentration has proved far more useful than listening to military experts simply ignoring such things; remember how the narrative of Ukrainian offensive genius quickly faded when Russia decided to mobilize equivalent numbers, thus preventing Ukraine from establishing massive local superiority?
Generally speaking there is no data at all on interceptor deliveries, making any assumption based on such incomplete knowledge is absurd. Only thing we get is the war propaganda from Kiev being parroted by loyal journalists and experts. And we know Kiev's war propaganda is aimed at maximizing foreign support in its struggle against Moscow , thus the general narrative will always be: Patriots/IRIS, etc works great, but we need more.
Which brings us back to the core question: Are Ukrainian Power plants now being destroyed because Ukraine is running out of interceptors or because Russia is now targeting Ukrainian power plants? A related question is: Has Russia previously been targeting Ukrainian power plants but failed due to interceptions?