Laird has made 15 league starts for MK, though came off after a bash to the shoulder during Tuesday night's 2-1 win over Plymouth.
Martin said: "Ethan did well to last as long as he did – he's still quicker than most even with one arm.
"Ethan gets kicked a lot because he's a threat. He's taken some really physical treatment in the last couple of games, and tonight he landed funny on his shoulder.
"I thought he might have to come off, but it was strapped up by [physio] Simon Crampton at half time and it kept him going for a bit.
"But he's exhausted as well. It's his first loan playing first team football in a team that demands so much of him with a lot of physical demand. I think he deserved a break for the last half an hour."