Webpack's website and marketing clearly tries to get us to use it, so although it's open source, the author (and contributors) from the project have an interest in people using their software.
In this case, they kind of pulled a bait and switch. They encouraged everyone to use it and then are letting them down by preventing them from using it efficiently on the basis of their own political beliefs.
It wouldn't be a problem if the project was advertised at the start as one person's work that comes with no guarantee of maintenance, support and if the guy suddenly goes crazy (whether because of political beliefs or otherwise) he might take down the project.
This one on the other hand looks serious, has good marketing, corporate sponsors, etc so while you can't ask for more, you at least kind of expect a serious project relied upon by thousands to not degrade existing stuff on the basis of political beliefs.
It's fine if you want to decide how your project is used (even for political reasons) but the proper way to do so is via the license so potential users know what they're in for before they start using the library and will (usually) refrain from using the library if the license does not allow them. This on the other hand is just a bait and switch and has tons of collateral damage to parties unrelated to, or even part of the BLM movement.
