Instead of using complex header example you can add hidden column to the end of tr, it’s hacky but simpler and shorter in my opinion:
<thead>
<tr>
<th> </th> <!-- column 1 -->
<th colspan="2"> </th> <!-- column 2&3 -->
<th colspan="2"> </th> <!-- column 4&5 -->
<!-- hidden column 6 for proper DataTable applying -->
<th style="display: none"></th>
</tr>
</thead>
<tbody>
<tr>
<td> </td>
<td> </td>
<td> </td>
<td> </td>
<td> </td>
<!-- hidden column 6 for proper DataTable applying -->
<td style="display: none"></td>
</tr>
</tbody>