I don't see any reason why such information (average pilot experience) can't be published based on a sample data. Other than worrying about the airline filing a lawsuit which shouldn't be a problem if you publish factual information and issue a disclaimer about the statistical probability for error.
The information should be published based on carrier name, not operator. Many large airlines outsource their flying to low cost operators who carry the name of the larger airline...such as the regional airlines in the USA.
The problem with the regional airlines in the USA is that they split their pilot pool across several code share partnerships so one day a pilot could be flying under the Delta Airlines name and the next day under USAirways or something like that. A solution could be to use averages based on number of flights used in each code share compared with experience average for that operator.
Then you have to place the data in a context that the public could understand and care about. For example...if airline A with 2000 pilots has an average experience level of 5000 hours and airline B with 3000 pilots has an average of 5500 hours....does that really matter to anyone?
I think whats more important is the general spread of the curve, not the average. For example, airline A has pilots that range from 250 hours up to 13,000 hours while airline B's lowest experienced pilot is 3000 hours.