Can you make the same conditional formatting on an attribute table added to the printcomposer as you can do within the attribute table? (with QGIS 2.16.3)
Don't think so, might be a good idea to post this as a feature request.
Saying that, there are some options which allows you to enable shading for matching cells in:
Item Properties > Appearence > Advanced customisation...
Since there are already existing options to apply shading to certain order of cells, it should be possible to add a custom expression somewhere.