NOTE: Members that reach 750 nights and 10 years at Platinum by December 31, 2018 will be grandfathered into Lifetime Platinum Premier Elite status (notified January 2019). In addition, members that achieve Marriott Rewards Lifetime Platinum under the legacy requirements by year end will also be grandfathered into Lifetime Platinum Premier Elite status. And, don’t forget that we’ll combine Lifetime activity across both Rewards and SPG toward qualification when members combine accounts in August. Beginning in 2019, qualification into Lifetime Platinum Premier Elite status will not be available. See FAQs for details.

So not comibining and saying that MR nights don’t count for SPG members when they are the acquirer would be really bad form. I won’t say I’d never stay with them again - but they definitely would become my 2nd choice and it would cement my commitment to Hyatt.