As another user posted, someone is impersonating this user in order to scam people. If anyone sends you a steam invite before contacting you through steamtrades, do not trust them.
I have not traded with this user, but I just wanted to put a warning out about THIS other user https://www.steamtrades.com/user/76561197962581702 who attempts to impersonate this reputable user by changing his steam profile to mimic them http://steamcommunity.com/id/RasieI_/ in order to scam people out of games. I just attempted a steam trade for the first time and was scammed by them. If you are reading this, please make sure you are trading with the REAL user (who I am sure is reputable and awesome) and not the scamming imposter!