I’m surprised that Musk is going through with this. It seems like this lawsuit would mean that Media Matters would be able to get access to lots of internal information via discovery.
Some federal circuits (e.g. the 9th) have protections against SLAPP lawsuits. The 5th circuit (where this lawsuit was filed) does not, and the district judge is Reed O'Connor (https://en.wikipedia.org/wiki/Reed_O%27Connor) who's infamous for rulings friendly to conservative causes.
The insinuation here is that the venue was chosen to get a judge that is less likely to rule against X/Twitter in those earlier stages and make it more likely that later stages of the trial will be reached.