Good effort, but they'll never win
I've been following this, mainly because I feel it's a good lesson for techies to learn -- even the most well-heeled company in the world does not consider IT strategic. This is a place that probably needs a fleet of armored trucks to collect the cash generated every day and take it to their bank, yet they don't want to pay full time employees to run the IT department. They will never win; even if they can prove discrimination, Disney's lawyers will have them tied up in court until they run out of money and give up.
The issue here is that Disney did this the nice legal way -- they outsourced to (I think) TCS, and TCS is the one using the H-1Bs to lower the labor costs and thus increase profit margin on the deal. The former employees should be going after the lax H-1B regulation and holding the IT services companies responsible for misuse of the visas. If they could somehow prove that they were replacing a US, say, DBA with an Indian DBA doing the exact same job, that would be a precedent setting case. The case would be further bolstered if they could prove that "training your replacement" meant teaching them how to do the job, rather than "here's how we do things in this particular environment." That would indicate that the H-1B wasn't being used for an exceptional skill set as these IT services firms like to claim.
I say it's time for a proper profession in IT. Rather than being a "techie union" it would be more like a lobbying group. It's time to admit that the only way to get legislation you want is to buy it, and take up a collection to do so. That would at least put IT workers on a level ground with Zuckerberg and others lobbying for cheaper labor.