At the time of writing, forge for 1.13 is not out yet. But on the page for OptiFine they say its 70% done. How are they testing the mod without forge?
Quit the speculation. Ama is the one holding things back with the delay in FG3. Then cpw will port whats his rewritten modloader stuff from his 1.12 branch, and then we start on Forge. There is no hidden conspiracy to delay things from getting to you. Shit just takes time (admitadly, ama is taking way more time then he should and its starting to annoy me as well, but whatever)
As for Optifine, its "70% done" because the guy is using the work input into mcpconfig and backporting it to the old tool chain so he can do all his jarmodding. This is not something you as a general user should do as you need to understand what youre doing. And the tools are being rewritten so that they can deal with the the things that have changed in the years since minecraft modding began.