Four studies examined young healthy individuals' willingness to take drugs intended to enhance various social, emotional, and cognitive abilities. We found that people were much more reluctant to enhance traits believed to be highly fundamental to the self (e.g., social comfort) than traits considered less fundamental (e.g., concentration ability)... Ad taglines that framed enhancements as enabling rather than enhancing the fundamental self increased people's interest in a fundamental enhancement, and eliminated the preference for non-fundamental over fundamental enhancements.
Now, while transhumanists may not think there's any normatively significant difference between 'artificial' enhancement and 'natural' improvement (through better nutrition, training, etc.), it must be acknowledged that the vast majority of people do see things differently here. So the mere fact that they aren't willing to take drugs to artificially enhance their empathy is not at all the same thing as not wanting to improve their empathy.
I don't see anything here to suggest that people wouldn't be willing to improve their empathy by (what they consider to be) more 'natural' means. (The paper even explicitly notes that people are happy to improve their empathy again so long as this is framed as "enabling" their true self to shine through, rather than externally imposing a new personality on them.) Am I missing something, or are some people just way too keen to be cynical?
Update: Note that according to Table 3 (at the end of the paper), only 25% of subjects reported that they "do not even wish to be better on this trait."