They didn’t say it’s offensive. They took an offence — as an individual. Insinuating that just because they’re based in a budget friendly country it doesn’t necessarily mean their output is of any less quality than that of their higher-paid counterparts (in the US presumably).

Which of course is totally not reflective of reality grounded in stats or anything. It’s just one in a thousand exception confirming the state of the tech world the OP has made a somewhat negative remark about.

This my interpretation anyway. Both persons are right in their own way.

So the OP said that there was "a team in Traansylvania making it a legacy codebase". The literal meaning is that there is a team of developers in a foreign country being paid less to do the same job. The other guy said it was offensive because he's implying something similar. He's also working in a foreign country for a US business. More of a joke about being offended. At least that's how I'm reading it.