It's not complicated. This is a normal sort of criminal enterprise. These rooms filled with SIM boxes are all over the world. The owners of them rent out the service to others -- letting them send 1,000 spam messages for a fee. One of the buyers of the service was indeed using it to threaten a politician. But this represents a tiny fraction (less than 1% of 1% of the SIMs normal use -- which is probably mostly phishing messages and other spam). It is a criminal enterprise and was used as some sort of political threat, but it's probably not set up by Russia or intended for that purpose.
These enterprises might not be setup by Russia directly but they might be setup by Russian criminal organizations which have been very active in the US over the last 20 years. That nobody in the current administration seem to be concerned with criminal organizations outside of some small or remnant groups from Latin America is very telling all on its own. This administration has never named any Russian gangs in official statements, even while they now dominate in some parts of the US.
That's easily falsifiable. Trump's DOJ and Treasury have multiple press releases regarding prosecutions and sanctions against Vory v zakone, thieves-in-law. Just search on either phrase and you'll see them.
Additionally, calling Venezuelan and Mexican cartels like CJNG small or remnant is extremely inaccurate, to be charitable. They are among the largest, best equipped, and most dangerous organized criminals in the world. You don't have be pro-Trump to acknowledge this fact.
