Large figures only triggers the first terrain attachment that it can making it cancel any other terrain including cards that would target the same part of the monster.
Well in a way it's a bug. I think the last part of his statement is refering to Beacons and possibly radiation.
http://forums.cardhunter.com/threads/dropping-dual-beacon-near-4-size-enemy.7548/ I'd say it's a bug when interacting with the new adjacent tile affection terrain. Because you can hit a small 1 square target multiple times with multiple adjacent terrain modifications, but you can't hit a larger target multiple times with multiple adjacent terrain modifications.
