OK.
But I don't think it is a huge problem, right? I mean, it's not like Ledger where everything is closed-source, it's certainly better than that. But also, it is not like other open-source hardware wallets where they give you unrestricted freedom to do whatever you want with the firmware. But if you're an end-user and you just want to install firmware or if you're a dev who wants to contribute back, then there is no legal issue.
As long as the codebase of the firmware is regularly updated and you can see all the parts of it, and all of the bugs & vulnerabilities that could be lurking about inside there, then there is still some validation that the cold wallet's code is acting honestly.
EDIT
That being said, they could've written their license differently to make it less redundant:
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject
to the following conditions:
rights under the License will not include, and the License does not
grant to you, the right to Sell the Software.
It certainly makes me think that a lawyer did not write this.