If you are truly a partner you are at risk. If the company is sued, loses money, etc, you share liability. If the 'partner' you describe does not share that risk, the partner is only euphamistically used. Using a term improperly would not be proof its definition is wrong.
Andy is more or less technically "right" in this debate, assuming that the definition of partner is "General Partner" and not "Limited Partner."
The whole point of partnership is "shared risk for shared gain." The most common and important coin of partnership Risk is financial capital. In the NFL, the owners take risks in many ways, but most notably by committing to contractual payrolls, by taking on debt for facilities and operations, by trying to build a Brand and by putting either startup or purchase equity into the franchise. So, for taking that risk they are entitled to the rewards of the upside in a disproportionate way. I really don't hear the players arguing that (obvious) point.
So, yeah, he's right on all of that.
However, a more contemporary and enlightened view of partnership would accept the above but acknowledge that there are industries in which the workers are, to a large degree, essentially irreplaceable as individuals and where the core business of the enterprise cannot reasonably be outsourced to alternative sources of technology or labor without a serious impairment of an enterprise's ability to conduct its business in a value-added manner. The NFL is clearly defined in terms of such an industry.
In addition, the identification of a franchise with some players is indeed part of the branding of that franchise, creating economic value for owners for many years, not only when such players are active but long after their retirement. Joe Montana still embodies his franchise's brand as do Bart Starr, the "Steel Curtain" and many other individuals, as, no doubt, will Tom Brady and Peyton Manning for decades to come.
In that sense, a player who puts his body, skills and future earning power on the line everyday he crosses onto a practice or playing field is indeed contributing human capital to the enterprise in a way that, to varying degrees, directly and uniquely impacts the enterprise's potential for success.
So, it's not unreasonable or out of the question for these players to see themselves as quasi Limited Partners in the enterprise of the NFL. They are, indeed, not risking financial capital but they are risking their human capital in a way that not only makes them essential and to a material degree irreplaceable to the success of the enterprise but which entitles them to considerations by those who are risking financial capital that go beyond the considerations that might normally be given.
Given the above and that, under the law, the salary paid to its players is the entirety of what a franchise owes to them, I think that wanting full and complete documentation of the, supposedly changed, financial status of the owners before ceding back to them billions of dollars of revenue generated by their play on the field is perfectly reasonable.