This is pretty cool, and I'd use it myself except ... I found the original method cumbersome as well, and in my search for a better way, I found @ccstone's Share to Keyboard Maestro Forum macro.
His macro does the stuff you'd normally do using the Share button, but adds some nice formatting to the post (hidden details for the code and screenshot), and importantly, cuts the text at the end and closes the new forum post that was created by the Share button.
When the macro is done, you wind up with the text on the clipboard, ready to paste into whatever thread you're replying to. Sometimes it seems to get stuck when trying to contact the forum, but it generally works very well for me.
-rob.