2 things to remember 1. they don't really like company especially russians, they are just fine by themselves. 2. there is always a concern for sickness to happen, I just would not risk it myself, just to have a play date, that they don't really need or want.
I agree with ddjm dont risk your tort if I remember right you are from Mass an it is getting cold down here for you to take him in and out just for a play date it is not worth it if he gets sick but it is your call
There is no need or want for your torts to get together...it will only make the humans happy as they think the torts are happy...introducing a friend for a short period of time can cause stress, territory issues (friend coming into the territory), fights, illness (transfer of parasites or colds), etc. Having a tort friend over to your tort's indoor enclosure is way different from keeping a heard of torts in a large outdoor enclosure after quarantine. Personally I wouldn't do it...your tort won't gain anything by it.
Torts arent like a dog.. they like to be left alone.. and watched.. not played with.
Yours is brand new.. you need to give him time to settle and adjust. Too much stress is not good or healthy.
Plus what has already been said.
They can be enjoyed in other ways.. but not like a social domestic animal.
;-)