This is a ridiculous statement. The backlash isn't over spending money to support open source software, which is obvious from reading the comments on the announcement. The backlash is about an open source project using the AGPL 3 license (right there in the project repository in the LICENSE file) is "selling licenses to use the software" while making vague promises that "nothing will be paywalled".

Yes, you can sell open source software but the way they're going about it is incredibly tone deaf and brings up real worry they'll change the license in the future, maybe making it not truly open source. Even if this isn't the case the communication is really terrible. Why should we trust them when they're already this ham-handed?