Misplaced alignment tab character for macro + token in tabularray environment

Question

For some reason there's a conflict if I try to use tabularray in combination with macro + token.

\documentclass{article}
\usepackage{environ}
\usepackage{tabularray}
\newtoks\mynames
\NewEnviron{Names}{
    \global\mynames=\expandafter{\BODY}
}
\newcommand{\Name}[2]
{%
    #1 & #2 \
}
\newenvironment{NameList}{
    \begin{tblr}{hlines, vlines, colspec = {XX}}
    First name & Surname \
}{\end{tblr}}
\begin{Names}
    \Name{James}{McGil}
    \Name{Charles}{McGil}
\end{Names}
\begin{document}
\begin{NameList}
    \the\mynames

%       James & McGil \ % this works
%       Charles & McGil \ % this works
    \end{NameList}
\end{document}

I get the following errors:

This is how it should look like: