Everyone who owns a share of Twitter is looking for capital gains.
If you think VCs more likely to accept their investment turning into a non-profit than public market investors, then you've never interacted with stock investors.
Twitter trying to turn into a non-profit would lead to a class action lawsuit for breach of fiduciary duty. Guaranteed. (If they even got that far without the board and CEO getting replaced.)
There are many things in the business world where you are at position A and will end up at position B, but there are too many stakeholders who are going to lose by the transition for it to happen peacefully.
That this has been forgotten and replaced with unilateral and antisocial concerns like "increase shareholder value at all costs" is an accident along the way. There is no reason why that can't be corrected.
Public corporations exist for the good of the public and are basically funded by the public - even more so if they are largely owned by pension funds.
My point, that being said, was not that this is straightforward. It is clearly not an easy step from public corporation to charity. However, that is a slightly easier step than from VC owned private company to charity, because VCs are very clear about wanting one thing only: capital gains, and they are not equivalent to "the public".