Clear evidence of Blockstream controlling the Core code base to prevent block size increase can be seen here
I'm not sure anyone is arguing against the claim that core or blockstream is trying to prevent, especially, a hard fork increase. Although they are probably calling for scaling but at a far slower pace than you think is safe and correct.
But nothing can justify not going form 1MB to 2MB, there is a real backlog and the safety limit is above 4MB.
Actually there IS something that can justify NOT doing this. By changing the transaction capacity in this way you change bitcoin's value proposition and you destroy its digital gold properties (ie an inflation hedge). This would tank the system. And also by doing so you open up these qualities and parameters to perpetual political debate which everyone agrees would be terrible for the long term health of the system.
More importantly though, you need a founded scientific argument to propose the system in order to change it, and since there isn't one, there is no hope of you getting your way. The entire security of the system is held together by science and guarded by (computer) scientists.