Ea says no bans for using sli, SLI away kids. https://answers.ea.com/t5/Technical-Issues/Sli-and-banned/m-p/7885816#M14214
SLI has been allowed in games in general for over 20 years. SLI has been allowed in Battlefield since Battlefield 1942 which was released in 2002. So yes, no bans for using SLI 
As above, EA has never issued bans for SLI.
EA have only ever banned for exploits and/or cheating, As long as you’re not in violation of ToS, You should be good.
Pity there is still no official BFV SLI Profile available 
You can use the starwars battlefront profile for sli. I have found it is the most compatible with this game
Yeah I know there are workarounds but you don’t get all the proper weather effects etc, would be nice to have an official BFV Profile like we had in previous BF titles.
With the post lately about how much pep’s are disliking bfv, EA/Nvidia may never SLI this game.
The guy who said he got banned for using sli, but EA’s response was for something else
You break our rules(https://www.ea.com/terms-of-service#section6) if you:
• use software that interferes with or disrupts an EA Service or another user’s account.
• use undocumented features, exploits or cheats in-game that disrupts an EA Service or another user’s account.
• use software or cheats that disconnects other users from the EA servers.
Any questions?