To really check all the variables I'd have to save my database before nuking the planet, then before sending in the geo survey, and then before sending in the Xenology team. If there is a difference between nuked and non-nuked planets in level (eg Abandon Outpost/Intact City) then I'd have to redo the thing again to see if there's a difference in level between non-nuked planets. This would establish whether the level of the ruins is set on system generation, or on geo survey (probably the former) as well as establishing whether nuking makes a difference. Then if there's a difference between nuked and non-nuked planets not in levels, but in installations, whether the difference is significant, or small enough to be random.
But, naturally, effort involved exceeds laziness at this point. If I wasn't so annoyed about losing three colliers, two DEs, and two DLs that at 50M km by size 1 ASMs going 69,000KM/s I'd be more ready to do all that, but rebuilding my fleet will take about a year (I'll wait for my new sensor suites and FC before retooling my yards) and meanwhile my FLCs are worthless versus these precursors. Maybe when I've cleaned up the mess I'll try both approaches.
Come to think of it, when recovering installations from a xenoarchaeological dig, hits to the planet from robot defenders don't decrease the number of installations to be recovered, even though they do destroy installations on the planet. This suggests that nuking the PDCs won't do any damage to the ruins.
