Sorry i'm not saying and sharing Avi Leob's and Michio Kaku thoughts because I think they are proof that UAP are alien, just showing clearly that at least two brilliant physicists believe it's possible for that to be the case. They have no issue with it. So the arm-chair comments that the universe is 'too big' or physics 'too understood' is not something the experts agree with you on. They are open, and possibly in belief, that the UAPs might be alien.
Yeah I don't think micho Kaku or Avi Leob for that matter has no issue with temporal paradoxes associated with FTL m8

they're a huge problem for anyone wanting to ftl and understanding the subject matter....its like a division by 0...Again, I think you're mixing up stuff/ reading what you want to read.
Avi Leob advocates that Oumuamua
might be an alien probe. Not that it travelled C plus or via a wormhole and broke reality, not that it contains little green men with telescopes on it..... A probe. Which could lead us to finally discovering concrete evidence of there (having been) alien life out there, (not in there) Hence me thinking its such an interresting case.
As for Kaku, he is (besides a "by necessity" string theorist) A futurist, much like carl Sagan... so when he has an open talk on Joe Rogan having a good time and wildly speculating on the absolute fringes of the maybe possible.. He does that in that capacity, not in his quote on quote "official" function as a theoretical physicis.
he's actually been called out on this
(which I don't think is completely fair by the way, you should seperate the futurist/science communicator from the actual scientific credentials)
Michio Kaku's specific field of scientific expertise is, like said, String or M theory.. things like "relativistic strings, loops and pomerons" This is a field of science consisting mostly of abstract mathematics. Real world application or even things like testability/verifiablity or possibility itself isn't even been taking into account in that subset.
and look, to extend a bit of an olive branch to you and
@Manofearth from the neh saying camp that i'm on concerning aliens visiting us in physics breaking objects... I'll go as far saying that is not impossible in the absolute sense of the word, But to quote from the article above.
"When tricky, biased observations are put up agains the laws of physics, I will bet on the laws of physics every single time."