This is rather superficial approach, and I think Notebookcheck should restrain from publishing such materials before they thoroughly learn the topic.
First, and foremost, there are no official sanctions (so far) which forbid selling civilian tech, including laptops, PCs etc., to retailers. So far, all exits of various vendors from the Russian retail market has been a voluntary action, not a compliance with sanctions policy.
Second, Lenovo and Asus have officially left Russian market, you can google for the official statements and news.
This article shows that the the author has no idea how relations between manufacturers and retailers work. Most of the retail products are realized through local partners. The manufacturer cannot force a local (Russian) partner to cease operations and stop selling their already delivered products. They can only stop the supply, but if the partners (vendors) have products in stock, they will sell them through all possible channels, and it has nothing to do with the manufacturer's policy.