This is actually scary, if someone falls for it. The consequences I mean.
I have received other messages from other potential clients asking to switch to hangouts and I just flagged them (read some older posts about it), but this guy kept messaging me pushing to move forward.
re: "but this guy kept messaging me pushing to move forward."
Upwork's messaging tool has a function for blocking any user from contacting you.
Your email software and instant messaging software and Skype all have similar blocking features.
Block this scammer in whatever communications tool you were using with him.