The result: the West Indies rattled up 507 and lasted just long enough to deny New Zealand victory when the anticipated rain arrived just before tea.
"Do I doubt the decision to enforce? Absolutely not," said McCullum.
"I think it was the right decision at the right time. If the rain had held, we would have got the result. There are times we'd love to have the other side from a luck point of view, but that's cricket.
"To get 600 and set the game up like we did, we gave ourselves a real opportunity. I thought we were excellent through the majority of that test and played some really good cricket."
However, Sammy was delighted by McCullum's decision: "Their bowlers toiled [224 overs in the back-to-back innings] and that's a lot of yards in the legs. So hopefully we can go into the second test and they'll be a bit tired and we will be a fresher team."
Sammy himself may struggle to make the start line at the Basin Reserve. He maintained his strained gluteal muscle, sustained on the second morning, was improving, although his limping between the wickets during his gutsy 80 yesterday would suggest only slowly. He is important to the team but may be severely limited in his third seamer role.
"I think with the combination of our squad, it's important that I am able to bowl - so I'll give it my best shot."
Sammy acknowledged the draw felt like a win, and had high praise for double century-maker Darren Bravo, labelling his 218 "a real mature innings. Somebody had to put their hand up for the team and one of the youngest guys did it".
"I guess Darren copied what Ross Taylor did and we batted around him. The key thing was occupying the crease. It is a moral boost for the guys, especially coming from India [where they were thrashed in a two-test series].
"We all know he's a class player. He models himself on his cousin Brian [Lara] and I guess even the great Lara would have been proud of that innings."
McCullum has his fingers crossed his seamers will be ready for the Basin Reserve after their hefty workload in Dunedin.
Last season it backfired on them against England, when after bowling 170 overs over the last two days, they then had to back up on days one and two of the next test for another 147 overs.
"It is a little concerning. We'll see how they pull up," he said. "They put in a tremendous amount of work over the last few days, but they're young guys and very fit and strong. I couldn't ask for any more than what they've given," he said. "[But] we'll have to think what the right thing is to do at the time as well."
He admitted New Zealand hadn't expected the West Indies batsmen to last as long as they did, "and you've got to give credit to them for doing so."
With an eye on the second test, injured batsman Kane Williamson is playing a Hawke Cup game for Bay of Plenty against Counties to test out the state of his left thumb, which was fractured in Bangladesh in October.
