That's not evidence against piling heaps of vegetation over the nests
and walking away, is it?
It's evidence against a buried-in-sand, sea-turtle style nest; it's not
evidence against a Mallee fowl style nests, though.
Mallee fowl only walk away a few hours before hatching. Before that, they
stay close, guard the nest to some extent, and do all that famous
temperature regulation stuff.
A sauropod nest covered with vegetation wouldn't be very hidden, unless it
was in the leaf litter of a forest, which doesn't fit the sedimentology of
any known sauropod nest (AFAIK) and would also be surprising because an
adult sauropod doesn't fit between the trees of a forest that's dense enough
to hide a sauropod nest.