So Bambu's argument hinges on "impersonation" claim of Jarczak's modified client using the same user agent string? If a user compiles official BambuStudio from source, does BambuLabs then also claim their non-bit-identical client is also impersonating the "real" BambuStudio? Or are they abusing user agents strings as authentication mechanism? If they don't consider it abuse, but rather legitimate use of agent strings…
Not saying Bambu is in the right here, but your view of how the law works is a bit lacking.