The former is Thompson's position, not the latter. That's one of the factors that went into the NRLC endorsement, according to articles in the last few days.
I agree with you on Fred’s position, and I speculate that the clarification issued on the subjet by his campaign was in part related to the NRLC endorsement, maybe a phone call saying “we can’t endorse you if you are saying you will oppose the platform plank on HLA (which is what he actually SAID on MTP, that he OPPOSED the plank), so his campaign came back and said he would NOT oppose it.