No, you are wrong. You need to re-read the post:

When the feature first entered field-testing, the system randomly selected a set of Trainers who were eligible for the EX Raid Battle. By taking Gym Badge level and total Raid Battles completed into account, we’re able to give Trainers who actively engage with the Gym where the EX Raid Battle is taking place and those who have invested more time into the Raid Battle feature a better chance of being invited to participate.

Initially, the players were "randomly selected." Now the invitation system has been changed, i.e., gym badge and raiding history will lead to "a better chance of being invited to participate."

The post was about what has changed. If it were no longer necessary to actually raid at a gym in order to receive a pass there, that change would have been specifically mentioned.