While your opinion may or may not be correct, unless Thompson has shared with you what his intention actually was it is, in fact,  just your opinion.  

I agree, it is never a good thing to embarrass your boss in public.  In Thompson's case he only works for four board members not the entire OPA membership, since it only takes four board members to hire or fire him.   If Thompson was truthful and accurate with regard to the board perhaps not doing due diligence, then I have a larger concern regarding this process than Thompson embarrassing some members of the board in public.   I say some members since you have commented that Terry, O'Hare and Cordwell didn't support going with Landscapes.