If their taxminimization strategy puts them into a region where they run the risk of having to pay huge costs in fines for their tax schemes then no. Just like they don’t have a fiduciary duty to maximize income every single day, which would have them forced to sell off everything not bolted down (we’ll actually even the stuff that’s bolted down) to get cash here and now.

They should work in the interests of shareholders, which tax avoidance in the extreme could turn out not to be.