I think their point about VPN is that a third party provider then could be compelled to disclose information about you. Since all your traffic routed through a single provider before hitting the remote proxy, there is now the potential for a single point of collection. When using Tor only, traffic leaving your computer is encrypted before hitting the first node which mitigates this threat. If the use of Tor is illegal for you, a VPN makes sense to hide its use-- but like you said, it is only hidden from the ISP. The VPN provider can still see that you are using it. In practice, how Tor is used should depend on the threat a person is trying to defend against.