No. I read LW for several years exactly because I am interested in rationality in the abstract.
I find it hard to decipher what exactly do you propose and why. Do you agree whith the second quoted text (i.e. that rationality is a ruse to propagate transhumanism)? Do you suggest that LW should be "honest" and replace the current tagline with "transhumanist propaganda website"? Or, on the other hand, do you suggest that the ruse is imperfect and the true purpose should be better hidden?
Concerning Less Wrong's tagline, consider this plausible reaction of someone looking at LW for the first time:
And here are two real quotes from 2009:
And in reply:
The quoted text speaks for itself really. So therefore I think LW's admins/web designers should seriously consider replacing the rationality tagline with something more savory.