It seems to me that the blood pressures (& reputations) of these folks would have been better served had they just taken the time to crack open a dictionary or, in case dictionaries are extinct in the U.K., conduct a search on Google & they would have instantly seen that "celebrate" has many meanings. Here's what I found (in 0.35 seconds):
Make no mistake, there will be celebrations in every sense of the word in Leicester next March. It will be the largest gathering of Ricardians in history, past & future, after all. Outside of the various religious ceremonies, people are bound to meet up in bars & restaurants, bend a few elbows, crack a some jokes, in short do what ever like-minded humans do whenever they gather in large numbers.
But just because we may be smiling & laughing from time to time does not mean we will be acting like that when any of the religious ceremonies is celebrated. Those will be solemn occasions & of course we will act accordingly.