if they had (assuming they have transcended the physical limitations of space and time) thats probably why we have no evidence of them

wellllll, depending on how much you want to believe from or read into Tom DeLonge's To the Stars disclosure efforts/Pentagon UFO vids (since they are the most "credible" ufo dudes out there at the moment) this may actually be the case. If you're at all interested, I suggest looking up NY Post's Basement Office series on youtube and going to other mostly reputable sources from there (NYT and stuff).

It's really hard for me to buy into some of the more outlandish claims associated with this group, but their ideas are interesting to think about.