ROWLEX OntologyExtractor behaves correctly (OwlGrinder reads ontologies and produce assemblies. OntologyExtractor reads assemblies and spits out ontologies). According to the OWL specifications, if there is no cardinality restriction associated to the OWL property, then its cardinality is assumed "zero or more". Should you want a property be not an "array property" then you need to apply the cardinality restriction. A shorthand for that is making the OWL property a functional property, where the cardinality is 0 or 1.
So all you need to do is remove the [CardinalityRestiction(1,100)] decoration and you have what you want.
[EDIT: responding on the comment]
I reproduced your case, removed the CardinalityRestriction, and OntologyExtractor produces the following ontology:
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:owl="http://www.w3.org/2002/07/owl#" xmlns:rdfschema="http://www.w3.org/2000/01/rdf-schema#">
<owl:Ontology rdf:about="http://www.test.com/MyOntology" />
<owl:Class rdf:about="http://www.test.com/MyOntology#Item" />
<owl:DatatypeProperty rdf:about="http://www.test.com/MyOntology#Name">
<rdfschema:domain rdf:resource="http://www.test.com/MyOntology#Item" />
<rdfschema:range rdf:resource="http://www.w3.org/2001/XMLSchema#string" />
<rdf:type rdf:resource="http://www.w3.org/2002/07/owl#FunctionalProperty" />
</owl:DatatypeProperty>
<owl:ObjectProperty rdf:about="http://www.test.com/MyOntology#MyArray">
<rdfschema:domain>
<owl:Class rdf:about="http://www.test.com/MyOntology#Container" />
</rdfschema:domain>
<rdfschema:range rdf:resource="http://www.test.com/MyOntology#Item" />
</owl:ObjectProperty>
</rdf:RDF>
This ontology allows you to create RDF files where your container object has zero or more items linked via MyArray OWL property.