This is actually more of just a really cool visual, but when Justin and Austin kiss, Austin is wearing a shirt and jacket that largely match the stained doors on stage. When the world turns gray during the kiss, he and Justin are more sharply in focus due to his shirt and jacket no longer blending in with the stage doors. This means that they no longer fade into the background, but are finally allowed to stand out and show their true selves to the world.
Actually, it's more than this. Earlier in the episode, Marc is telling Justin what kissing someone while being in love feels like and he tells him something along the lines of "It feels like the whole world around you fades away until only you two are left".
If Calvin Hartley investment in Meade was as a silent partner only, wouldn't it have been a breach of contract when he started making changes? Surely Meade could have sued him for this and potentially recouped at least some of their losses from the whole Connor debacle?