I don't want to be negative but I should point out that there was a petition to save potco and that didn't work so it's highly likely that this petition won't work. There's always a little bit of hope though, good luck.
Apple has shown a total disinterest in public outcry. Their goal is to lead the market, and they've always been this way. The headphone jack debacle spawned hundreds if not thousands of tweets, petitions, YouTube videos, and blog posts, because it impacted the general public. OpenGL is a rendering API (a legacy one at that), and something only a small subset of people (mainly developers) will ever have to worry about. I hate to admit it but this will never get the backing it deserves, and certainly not with the name of a small project like TLOPO attached to it.
Some people might say they've been trying to kill OpenGL and OpenCL for awhile now. They will almost certainly never back down from this.
I would recommend changing the focus of the petition to saving OpenGL in general, and in your description focusing more on how widespread the issue really is, and how many people this will affect, if you want this to get anywhere. Spread it around programming Discords, forums, subreddits. Maybe some blogs will cover the story and mention your petition if it gets big enough. This focuses too much on TLOPO, something most people will not know about, and by extension, not care about.