Why limited to xpath pattern?

Using xsh2, which I hate :) the following works

$ cat jonk.xml
<a>
  <b>
    <c>not match this</c>
  </b>
  <b>
    <c>but  match  this</c>
  </b>
</a>

$ cat jonk.xsh
open "jonk.xml";

#~ foreach /a/b/c {
foreach //c {
    if xsh:matches( text(), '\b\s{2,}\b' ) {
        pwd;
        echo text();
    }
}
$ xsh -q jonk.xsh
/a/b[2]/c
but  match  this
[download]

See XSH2 Reference, Flow control