Sharing account question

Now I know Riot says no sharing accounts but is that just in general or is it if that other person intends to rank? My brother in law just started playing about a week ago and of course has like 0 champions minus the free rotations. If it was allowed I wanted him to try out champions, in bot games only, to see ones he likes and would want to save up for....but if this isn't allowed and will get my account banned (or the possibility of being banned) I definitely won't do it. So just curious....