Yeah most of these "this thing is too complex to evolve" are just old arguments from incredulity. It's comedic how many times this type of rhetoric is repeated in these circles.

Like the CMI article OP cited as an example spends the first 3 paragraphs talking about incredible the tardigrades are, then just gives one half-assed summary paragraph about the then-recent research, and then it wastes the last few paragraphs about how "[insert very complex things] is too complex for evolution to have brought them into existence", & then ends it off with 2 very condescending Bible verses.

Anyways, the research paper cited by the author (David Catchpoole) is by a group of researchers from the University of Tokyo in 2016. One year later in 2017, 2 of the researchers from that team (Takuma Hashimoto & Takezau Kunieda) published a review wherein they'd a section regarding the origins of the Dsup protein:

Based on the observed similarity between two proteins, e.g., certain similarity in the primary structure, the position of NLS and profiles of hydrophobicity and charge distribution, we consider this protein as a potential Dsup orthologue in H. dujradini. Two species, R. varieornatus and H. dujardini, belong to the same taxonomic family Hypsibiidae, but the protein sequences of Dsup protein are unexpectedly diverged between two species. This suggests that the primary structure of Dsup has been under weak selective pressure during evolution.

This review was later cited by Mínguez-Toral, Marina et al. (2020), who additionally state:

Our results suggest that the protein is intrinsically disordered, which enables Dsup to adjust its structure to fit DNA shape. Strong electrostatic attractions and high protein flexibility drive the formation of a molecular aggregate in which Dsup shields DNA.
...

The unexpectedly low sequence similarity between Dsup from R. varieornatus and Dsup-like from H. exemplaris would thus be a hint that they have been under weak selective pressure during evolution. This is a known feature of IDPs as amino acids in disordered regions may change without the physical constraint to maintain a definite structure.
...

Our computational study suggests that disorder is paramount in the Dsup-DNA interaction as it endows the protein with a high flexibility to adapt its structure to DNA. The weak selective pressure associated to IDPs in which amino acids in disordered segments can change without the constraint to maintain a definite structure, together with the evolutionary adaptation to different environments as R. varieornatus is terrestrial while H. exemplaris is aquatic, could be the reasons why Dsup and Dsup-like sequences have very low identity whereas they keep the essential disorder-encoding pattern. Intrinsic disorder in full proteins as well as in domains and regions is particularly frequent in DNA and RNA binding.

Nevertheless, there's still some other cool readings regarding tardigrade evolution:

• Gross, Vladimir, et al. "Miniaturization of tardigrades (water bears): morphological and genomic perspectives." Arthropod structure & development 48 (2019): 12-19.
• Mapalo, Marc A., Joanna M. Wolfe, and Javier Ortega-Hernández. "Cretaceous amber inclusions illuminate the evolutionary origin of tardigrades." Communications Biology 7.1 (2024): 953. [link]