What are the connotations of "Kiryas Chutzos"?
Rashi: It means a town full of market-places, teeming with men, women and children (of Mo'av) - as if to say 'See and take pity on all these people; that they should not be destroyed!' 1
Targum Yonasan: It means a major town that belonged to Sichon called Birosha whose streets were walled. 2
On a number of occassions, Bil'am showed no pity when he sided with Par'oh regarding the sunjugation of Yisrael. It is not unusual however, for Nochrim to act compassionately towards one another - and even towards animals - but to treat Yisrael with the utmost cruelty, as we have seen in recent history and continue to see in modern times.
See Na'ar Yonasan, who does not understand what Targum Yonasan is trying to tell us. See also Peirush Yonasan.