Edit: he might be talking about https://github.com/matrix-org/synapse/issues/4787? Except that was fixed a month ago...
In terms of "don't blindly believe what a for-profit is saying, especially one that is in full control of the said protocol", I'd agree, were it true. However:
* These days the protocol is controlled entirely by the non-profit Matrix Foundation.
* The majority (3 out of 5) of the Foundation's directors have zero affiliation to New Vector, the company that the core Matrix set up to try to keep the project funded.
* The governance of the foundation & protocol is entirely open, as per https://github.com/matrix-org/matrix-doc/blob/matthew/msc177...
* We're announcing the final board once formally appointed; due in the next few weeks.
Meanwhile, it's also true to say that you shouldn't believe the skewed perspective of a disgruntled ex-community member with a chip on their shoulder, who is trying to plug their hostile fork: https://news.ycombinator.com/item?id=19473694.