Basically the virus is weak. But the virus is capable of changing and adapting and this guy is saying that the vaccines will aide the virus in doing so faster, which could result in a much worse variant. This is possible with infectious agents. I think all these asshole "scientists" need to sit down.

Antigen escape:

"This occurs when the immune system is unable to respond to an infectious agent. This means that the response mechanisms a host's immune system normally utilizes to recognize and eliminate a virus or pathogen is no longer able to do so."

https://en.wikipedia.org/wiki/Antigenic_escape#:~:text=From%20Wikipedia%2C%20the%20free%20encyclopedia%20Antigenic%20escape%20%28alternatively,pathogen%20is%20no%20longer%20able%20to%20do%20so.