If they become broadly accepted beyond one person's interpretation...sure. But, no one else in the business world accepts this re-definition. It would invalidate all the legitimate examples of being the actual "founder" of a company.
That term comes with a higher level of significance. Applying it to anyone who comes onboard later, or to a new owner of a preexisting brand, would dilute the significance of the foundational contribution the original owners made to that brand.
But, this is obviously why Elon Musk is trying to commandeer that title for himself. He is attempting to apply a greater level of significance to his role in the company. Which is laughable, considering he's already made a sizable contribution to its success. Calling himself a "co-founder" on top of that, is just a transparently presumptuous lie. Anyone who looks into the history of the company will know that it isn't true...unless they re-define what it means to be a "founder".
And that is just as ridiculous as making the claim in the first place. You guys are embarrassingly gullible for just going along with his bullshit, like it doesn't stink.