ProtonVPN is no competitor to Private Internet Access in terms of the size and the number of users. If you were a co-founder of PIA, would you risk your reputation by publicly providing false accusations against a company 1/100 of the size of yours?
That's the problem. I haven't found any of his statements, that would be only half-true. I even discovered a conference held in Lithuania in 2017, where one of the speakers was presented as the head of B2B sales at Tesonet, working on Oxylabs[1]. It is very unlikely, that ProtonMail was not aware of who it was partnering with on a free VPN service.
Furthermore, after it was pointed out by the co-founder of PIA, that the CEO of Tesonet is the director of ProtonVPN UAB, the company was renamed multiple times in two months[1], with its director now hidden from the public view.
Finally, the IP blocks, which belonged to Tesonet and were used by ProtonVPN just a few months ago – despite the co-founders of ProtonMail publicly denying any technical partnership between the two[1] – now belong to ProtonVPN[2].