Before I go into my answer, I should point out that where the psychoanalytical theory of psychological defence mechanisms originated from Sigmund Freud, his theories are considered by many to be pseudoscientific. More can be read in my answer to this in meta
The Gnomes concept in the LiveJournal Blog does not fit any definition of the defence mechanisms.
Psychological Defence Mechanisms
In psychoanalytic theory, defence mechanisms are psychological strategies brought into play by the unconscious mind to manipulate, deny, or distort reality in order to defend against feelings of anxiety and unacceptable impulses and to maintain one's self-schema or other schemas.
Saul McLeod (2009) provided a list of all of the psychological defence mechanisms put together by Sigmund Freud.
These have Medical Subject Headings (MeSH) number F01.393, and if you look at the MeSH Tree Structures for F01.393, these are expanded providing the following (NIH, 2018):
A Different Take on Defence Mechanisms in LiveJournal Blog (Evolution, 2017)
Taken from the question, and an English translation is available here.
In her blog, Evolution explained...
Gnomes, or rather dwarf caps, are such psycho-protection that people use to explain themselves the indifference of a partner.
Stupid, Stesnyasha and Bednyasha, remember?
Not only women, but also men like to put such a cap on the figure of an interesting person.
Why is this done?
Around then, why do people wear crowns.
When one wants to get something from a person, but he does not give (usually love, recognition, approval, respect, in general food for self-esteem), it is necessary to extract something from it, for which the crowns and caps are used.
You need to wear a crown (imagine yourself powerful and significant) on your figure, and put a stupid cap on the figure of a person (imagine him stupid and dependent) and then from the height of his greatness, considering the defectiveness of the second, to help him give you what you want to take.
This does not fit any definition of the defence mechanisms developed by Freud, or expanded in MeSH. What is being described here is domestic abuse through manipulation and coersion via demoralisation of the significant other.
Evolution (2017). Gnomes [Online]
Russian Original: https://evo-lutio.livejournal.com/591726.html
English Translation: https://translate.google.co.uk/translate?hl=en&sl=ru&tl=en&u=https%3A%2F%2Fevo-lutio.livejournal.com%2F591726.html
McLeod, S. A. (2009). Defense mechanisms. [Online]
Retrieved from https://www.simplypsychology.org/defense-mechanisms.html
NIH (2018). Medical Subject Headings (MeSH) [Online]
Retrieved from: https://www.nlm.nih.gov/mesh