They are a distributor of the ETI Thermapen and nothing more except 'good friends' with the owners of ETI and that they have contributed design ideas to some versions of the Thermapen. Just as any distributor does. Note how they try to make it sound like they have some sort of ownership of the product, but the only thing they have ownership of is the Thermoworks name and a contract with ETI to be the sole US distributor.
What in their blog post makes you think they have the right to claim copyright infringement for someone selling a Thermapen they bought directly from ETI?