My home ISP certainly can route packets to both HE and Cogent:
root@tranzistor:~# ping cogentco.com PING cogentco.com(cogentco.com (2001:550:1::cc01)) 56 data bytes 64 bytes from cogentco.com (2001:550:1::cc01): icmp_seq=1 ttl=56 time=21.1 ms ^C --- cogentco.com ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0msrtt min/avg/max/mdev = 21.107/21.107/21.107/0.000 ms root@tranzistor:~# ping he.net PING he.net(he.net (2001:470:0:503::2)) 56 data bytes 64 bytes from he.net (2001:470:0:503::2): icmp_seq=1 ttl=49 time=164 ms ^C --- he.net ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 164.454/164.454/164.454/0.000 ms root@tranzistor:~#
Why are packets from cogent to HE not routed via my ISP?