Well, that would be one of the ugly reasons I can think of, it just confirms that a double standard exists. Besides, Nereid specifically claimed to write a rebuttal on Arp; if you claim something like that and then walk away in the middle of the process it could mean Nereid feels it isn't worth the hassle, or the rebuttal can't be written. It would be honest to at least respond and tell us what is going on.

Personally, I think Nereid has realised that Arp et al. really have a point and doesn't want to discuss the matter in any more detail in the forum in order to avoid having to concede the reality of an intrinsic redshift component. Possibly this is a general reaction of mainstreamers when confronted with evidence against something they believe to be true and more so if they at first assumed the proposal was already proven to be "crackpot". How does one acknowledge not just being mistaken, but having been positively caustic and dismissive without "losing face"? Avoid and ignore is the easy way out.

Cheers.