Not inherently, no, but it is when used fallaciously. Like in this case.
It never is. There might be some other logical fallacy at play. Slippery slope is a common one in cases where people cite reducto ad absurdum. But why not cite the actual fallacy rather than the one that isn't a fallacy at all?
Or maybe don't. Generally, logical fallacies are better used to pick apart your own arguments rather than tossing them in other people's faces.
Just like deliberate hyperbole is not a fallacy when used skillfully and transparently to underscore a point, it’s the context and the delivery that decides whether something is a valid reducto ad absurdum argument or a reducto ad absurdum fallacy.
Nope. There is no such thing as reducto ad absurdum fallacy. I challenge you to find a citation otherwise, because I can cite a lot of stuff that talks about its use as a tool of logic and does not mention fallacies what so ever, or does so only as part of connected information.
https://en.wikipedia.org/wiki/Reductio_ad_absurdum - "In logic, reductio ad absurdum (Latin for "reduction to absurdity"), also known as argumentum ad absurdum (Latin for "argument to absurdity") or apagogical arguments, is the form of argument that attempts to establish a claim by showing that the opposite scenario would lead to absurdity or contradiction". The word "fallacy" does not even appear on the page except as a link to "See Also - Argument from fallacy".
https://www.britannica.com/topic/reductio-ad-absurdum - "reductio ad absurdum, (Latin: “reduction to absurdity”), in logic, a form of refutation showing contradictory or absurd consequences following upon premises as a matter of logical necessity." Fallacies are only mentioned further down the page as connected information.
https://www.merriam-webster.com/dictionary/reductio%20ad%20absurdum - "1) disproof of a proposition by showing an absurdity to which it leads when carried to its logical conclusion 2) the carrying of something to an absurd extreme" Again, no mention of fallacy. It's a tool to disprove something.
https://www.logicallyfallacious.com/cgi-bin/uy/webpages.cgi?/logicalfallacies/Reductio-ad-Absurdum - "A mode of argumentation or a form of argument in which a proposition is disproven by following its implications logically to an absurd conclusion. Arguments that use universals such as, “always”, “never”, “everyone”, “nobody”, etc., are prone to being reduced to absurd conclusions. The fallacy is in the argument that could be reduced to absurdity -- so in essence, reductio ad absurdum is a technique to expose the fallacy." Note that last sentence. Reducto ad absurdum is about exposing the fallacy, not creating one. This on a web site that's all about logical fallacies, and they ain't saying it's a fallacy.
https://www.cs.utexas.edu/~dnp/frege/reductio-ad-absurdum.html - "The Proof by Contradiction technique that we just described is a special case of a more general reasoning strategy called reductio ad absurdum. (Translate this literally as, “reduce to absurdity”.) We can use this more general strategy in everyday rhetoric as well as in mathematics". Again, no mention of fallacy.
https://philosophy.stackexchange.com/questions/69916/is-reductio-ad-absurdum-a-fallacy - Top level response explicitly says it's not a fallacy.
Edit: a few more to pile on.
https://www.quora.com/Which-type-of-fallacy-is-reductio-ad-absurdum-Whats-its-definition-example-how-it-works-in-real-life-situations - Top level response explicitly says it's not a fallacy.
https://www.thoughtco.com/reductio-ad-absurdum-argument-1691903 - "Like any argumentative strategy, reductio ad absurdum can be misused and abused, but in itself it is not a form of fallacious reasoning. A related form of argument, the slippery slope argument, takes reductio ad absurdum to an extreme and is often (but not always) fallacious. " Here again, the argument might be making a fallacy, but reducto ad absurdum is not it.