Even if it gets accepted quickly in the Arduino-ESP8266 repository, it will not be used instantly by PlatformIO. It’ll just be there sitting in the master branch. PlatformIO only updates its internal Arduino core package when a new release comes out, see here.
You can of course use platform_packages to tell PlatformIO to use a bleeding-edge git version of the Arduino-ESP8266 core, e.g. as covered some time ago in Custom framework and toolset for Arduino ESP8266 3.0.0 - #2 by maxgerhardt, by adding
platform_packages =
framework-arduinoespressif8266 @ https://github.com/esp8266/Arduino.git
to the platformio.ini of the project.
This will then however be a per-project fix. And you will have a slight discrepency between the 3.0.0 release version of the core and the bleeding-edge git version of the repo, potentially causing bugs.
So, I’d rather advise to do the change once locally in platformio-build.py, this way it automically fixes it for every project using this core, without using special instructions. In the core version after 3.0.0, this will be fixed automatically then if the PR is accepted and PlatformIO updates to it.