I'm not sure.
Section 2.2 says version is a number and "For this version of XSLT, the value
should be 1.0. When the value is not equal to 1.0, forwards-compatible
processing mode is enabled". Similar phrasing occurs when version is discussed
elsewhere in the spec.
I think there's room to argue that since they said to compare "the value" and
declared that these are numbers, 1.0 and 1 are equal. They show an example of
testing version's numeric value:
<xsl:when test="system-property('xsl:version') >= 1.1">
But even granting that this may not be technically necessary, I don't have any
objection to changing how we display the version number to agree with XSLTC