Sacrilege,
That is a copout. There are frozen brands out there (with heimish hechsherim) that were checked a few years ago and were found to have bugs. My guess is that the Rav is not in the kashrus industry. A kashrus question such as this needs to be asked of someone in the industry. They know what is done and can give an opinion, to say eat a certain brand and only that brand is motzi la’az on the other brands unless the Rav has personally looked into the other brands and found them lacking.