The Court is always political, in that it decides on political matters. Give the way the court is described (often innacurately) regarding its 5/4 split, we can assume that some decisions are “political.”
However, those politics are better played if you decide that “original intent” is conservative/right, and “living” is liberal/left.
For this case, the key question IMHO is wrapped up here: “after the alleged unlawful employment practice occurred.”
The Court seems to argue that the practice is on setting the salary, not with each subsequent paycheck. If the Democratically controlled Congress does not like this, they can change it. If it is such a slam dunk, then they can overcome a Bush veto.
However, opening the doors to never ending discrimination lawsuits with no timeline might not be the best thing for business in America. We do NOT pay everyone the same. All candidates are NOT equal. All jobs are NOT equal, even if they are in the same pay grade. We have had threads in the past that discussed why women get paid less, for example. The larger issues are that women drop out of the workforce, and that women do not ASK for more money.
However, sometimes people do not know that they are underpaid compared to peers. Sometimes, however, they do:
I work in education, specifically working for the State of California. My pay, and the pay of all of my staff, and the pay of all of the faculty - is public record. You can request my pay level. My staff regularly request the pay level of their peers during annual review time. They then typically find out that I pay better than most other departments on the campus, and they are happy.
I worked long ago for a firm where everyone had a billing rate, and that rate was a function of salary. Once I started running projects, I learned how much more others made when I put together invoices. I used that in salary negotiations. A female peer did not - she did not want to rock the boat.
Should we make all salaries at the firm open data?
Finally (then I need more coffee): Perhaps Congress was trying to put a cap on never ending lawsuits by saying that if you have an issue, you have to bring it up immediately. If not, we would find GM being sued for hiring decisions made in 1973.