Weather companies like Accuweather were annoyed by the National Weather Service releasing weather data in KML form -- they saw it as a threat to their lucrative business of selling public domain weather data. Sen. Rick Sanatorum tried to come to the rescue with a bill that would limit their ability to release that data.
It is good IMO for a rep to fight for legislation that helps local businesses when that action serves his constituents as a group over the long term.
That's not the case here because what Santorum did is attempt to artificially block competition in a space where competition is likely to benefit all of his constituents in the long term. It's selling out the majority for the sake of one small business and creating a wasteful bit of government that small gov types like Santorum ought to be fighting against. It's creating a barrier to free market completion for the sake of a small win for one small company.
Of course, all those arguments miss the point. The weather service is an important function of the government, we shouldn't have to pay for weather. It's a matter of public safety and information, the property of the commons, not some commodity. Protecting that is the reason we have a government, not to artificially support a Senator's local business.
To expand on you reasoning a bit I think there is a general test we can apply to all government data collection and publishing practices. If the data is being collected then its been determined to be in the public's interest to do so and therefore it's also in the public interest to release it freely in a reasonably accessible format. If the set is not useful then releasing it serves to at least inform citizens that we're wasting money so we can exert pressure to stop collecting the useless set.
The exception of course is gov data that may have privacy or security implications but nevertheless eventually it should be released when those concerns are no longer valid.
The job of the government, and in this case, the senate, is to represent the populous, in this case the state, not play special party to any particular organization.
Accuweather has fewer than 500 employees many of whom are not even in Pennsylvania, meanwhile Pennsylvania has a population of almost 13 million.
So why exactly is it that you think it is 'just', 'correct' or any other possible form of 'right' for this senator to support this company for any other reason than it being in the best interests of his _true_ constituents? That is, the people he represents that are not in the, at most, ~.0035% of his states population that work at accuweather?