Here is the stat block for playing a Kender in AD&D. You will notice that no where in it does it say the player must steal from his party members. In fact it doesn’t say you have to steal at all.
Three pages of information are presented about kender in the book. The stat block takes up about one page. That leaves two pages of information that you have not included here.
On page 53, under
Society it states "Kender society can also be hard to take. Nonkender visitors rarely stay longer than a week in any major kender town, unless they have a great sense of humor.
It is not uncommon to be relieved of one's possessions at every turn (occasionally by the constables themselves). Visitors are pelted by a constant barrage of questions and told a million lies and tall tales without rest or letup." (emphasis added)
On page 52, under
Theft vs. Handling it states: "The intense curiosity that kender feel feeds their desire to know how locks can be opened...and
how to reach into pockets or pouches to find interesting things to look at.
Thieving comes naturally to them - so naturally that they do not see it as thieving." Also: "To be called a thief is still considered a base insult. This assertion sounds remarkable in view of the fact that
kender constantly borrow things from each other and from visitors (without asking) in their communities. Kender don't regard their idea of borrowing as stealing, however.
If they need something, they'll take it." (emphasis added)
If someone actually argues that they are forced to steal from players if they play a kender, yes that is an awful player. But that's the strawman version of the argument against how kender are presented. The steelman version is
kender are presented in a way that encourages in-character behaviour likely to aggravate other players.
This encouragement, in addition to being present in the fiction, is shown above. While technically the passages make reference to kender behaviour in their communities, there is nothing to indicate their behaviour is any different outside of them. Indeed, the fiction indicates that they do behave the same way outside of their communities.