You can hack around the lack of colspan support by adding an “invisible” cell for every cell that’s eliminated:
<tr>
<td colspan="3">Wide column</td>
<td style="display: none;"></td>
<td style="display: none;"></td>
</tr>
<tr>
<td>Normal column</td>
<td>Normal column</td>
<td>Normal column</td>
</tr>
DataTables doesn’t complain, the table renders normally and sorting works (invisible columns sort as the empty string).
I haven’t tried this with rowspan.