Your comment title is obvious, but your conclusions aren't.

1) There are many other threats to our survival other than impacts. Many of these threats including impacts (at the large/fast end occupied by LP comets) can be partially mitigated by getting our eggs out of one basket.

2) Dealing with the impact threat includes developing technology of relevance to colonizing space so the two issues dovetail more than they conflict.

3) Since you site Yeoman as the leading impact rate authority and he states the average interval for the entire Earth for Tunguska class objects is at least 100 years and only 10 % of the Earth's surface is densely populated (as opposed to areas like Siberia) impacts in populated areas should happen on average less than once every 1000 years. Thus, it is quite likely that colonization could be well under way before even a Tunguska class event hits a populated area.

Colonization is likely to give us far more ability to deal with any class of impactor by giving us more launch points around the solar system and more routine space travel (ie launch on demand) in addition to better launch technology and detection capabilities.

Regards,
Mark

PS Why do you keep basing your radiation conclusions on one verbal source rather than the numerous book and internet site sources provided in recent posts? Doesn't sound like an open mind to me.