Coldfusion type="numeric" bug/feature

A couple of my coworkers stumbled on an interesting issue. Here are simple tests.
Thanks Jamie for additional tests and findings.
<br /><cfset testVal = '1,3,5' /><br /><cfdump var="#isNumeric(testVal)#"><br /><br /><cfdump var="#isValid('numeric', testVal)#"><br /><br /><cfdump var="#testFunction(testVal)#"><br /><br /><br /><cffunction name="testFunction" access="public" output="false" returntype="numeric"><br /> <cfargument name="foo" required="true" type="numeric" /><br /> <cfscript><br /> return arguments.foo;<br /> </cfscript><br /></cffunction><br />
Results in this output...

NO
YES
1,3,5

It seems that type="numeric" argument in the testFUnction should fail but it doesn't.
Also isNumeric(testVal ) doesn't agree with isValid('numeric', testval) though ColdFusion documentation says it should:
"float or numeric: a numeric value; equivalent to the IsNumeric function."

Also we confirmed (thanks Brian) that this exists in ColdFusion 9 beta.