You need to really ask the most important question.
Why would a new member be willing to take anyone on a time travel adventure with no guarantees you'll ever make it back to this timeline or the time you left. Let's assume, he is the first real card-carrying time traveler to start posting here. What is his motive for allowing fellow members that he has never met, to partake of a time travel adventure. Follow members: it makes no sense to me, why anybody would do that without alternative motives.
Yes because he knew that most of us would easily blow away his claims, and therefore he would avoid being humiliated on the main thread, and speaking in private would also help to maintain his status of being a time traveller..