This is why I always advise people to wait a few more years before using hardware wallets to store significant amounts of Bitcoin. They are too new, untested and unstudied and due to this they may have undiscovered flaws like this, in fact my opinion is that there are many other side-channel attacks similar to this, however in a few years once they have been better studied, tested and improved and we fully understand all the security concerns involved then hardware wallets will really shine.