I assure you I am not trying to play the victim.
It sounded like you were trying very hard to find offense by applying one meaning to a word that we all know has many.
Just see it from my perspective. You, I am sure, have encountered "sinfully" in many different ways, with several different meanings. One can act sinfully (sin against God, or sin against man). One can say a cake is sinfully delicious. One says "guilty as sin". And even in the UK using the meaning "unreasonably" is very common.
"Sinful" is a real word with several different meanings. Before playing a victim by taking offense you would have done well to have consulted a dictionary.
I looked it up in Merrium-Webster dictionary to confirm "sinful" meant "unreasonably" rather than just taking it as a common phrase here. It took less than a minute.
So you were wrong in two ways. First, a saying is not always the sum of its words (although in this case, it is). Second, "sinful" means "unreasonably".
Today people seek to be offended, and they find what they are looking for even if it is of their own making. I am not sure exactly when this victim mentality became popular (that was not the case when I was growing up, at least in the US).
Now...if this were a thread about sins then you would have a point. But Christians need to stop playing the victim. We have the victory. We have to stop crying at the drop of a dime.