TL;DR source is garbage, and porting 3DS models to switch is already proven to be possible
Except, no, this doesn't make sense for multiple reasons.
First off, the reddit post linked in this article links to a Nintendoeverything summary of Silconera article. Said Silconera article is itself a summary (because Nintendoeverything is just fucking lazy) of a translated Famitsu interview. Silconera never provided their own translation, just summarized it.
Here is the original Siliconera article. There is a mention of "a need to redo the models" but since we have no idea how accurate Siliconera's translation is this could mean several different things.
Exporting 3D models is not hard. The 3D models in the 3DS titles all come in a .dae file which basically every modern 3D modeling software accepts. The 3DS models have been ripped and ported into everything from Blender to Source Filmmaker. There are tutorials online on how to do it and there is an an entire database of ripped pokemon models online
Not only that, but Let's Go P/E have already been proven to use the 3DS models, so porting 3DS assets to switch is already proven to be possible
There is no possible situation in which Game Freak cannot port over models to the Switch. This discounts the fact that GF and Creatures both have access to the source files (as in, the original models, made in whatever 3D modeling software the company uses), so GF doesn't even have to rip their own models from the 3DS.