He explicitly wrote: "I thought long and hard about building a tool to solve this problem. Others, like pip-tools, already have. But, I don’t want another tool

He explicitly wrote: "I thought long and hard about building a tool to solve this problem. Others, like pip-tools, already have. But, I don’t want another tool in my toolchain; this should be possible with the tools available." so it's not like he's not aware of pip-tools.