He probably suspects that they have been all affected and figures it is best to just start over. Thrips like lighter colored blooms over those with deeper hues.
Some of the instructions for getting rid of thrips that I have read say to prune and destroy infested plant parts to get rid of the thrips and also to get rid of dead or dying tissue. You can try releasing beneficial insects or prune & apply chemical insecticides before they get back into the new flower buds. Some people use sticky traps to detect them.