Walker made the decision to ‘retire’ tailender Julian Atkins, therefore ending the game, after the player - batting at No 10 - had been struck twice on the helmet.
Walker had earlier seen young Charlie Whitfield forced to retire at the end of the 13th over after being hit on the hand, leaving him unable to grip the bat.
Walker came onto the pitch to talk to Atkins after he had been hit the second time, by a delivery from former Hampshire all-rounder and current Northants professional Gareth Berg.
‘I wouldn’t say it was hostility, but Julian had taken two flush hits, which can happen at any level of cricket,’ Walker told The News.
‘He wanted to carry on, but I could see he was visibly shaken. You could see it had rocked him.
‘As the captain, I have a duty of care to my players.
‘I was not going to allow him to stay out there and potentially take another blow.
‘The game was over, we had been outplayed from the start, we weren’t going to save the game. There was nothing to gain (from batting on) so I just thought ‘enough is enough.’
Whitfield had been struck by a delivery from New Zealander James Hartshorn, who has played first class cricket for Wellington.
Hartshorn ended with 1-36 off 14 overs, but it was Berg - who played the first five games of the Championship season for Northants this year at the age of 41 - who did the most damage with figures of 10.4-5-13-4.
‘Two first class bowlers,’ said Walker. ‘You don’t come across too many attacks like that (in the Southern Premier League).
Asked to chase 284 for victory at Havant Park, Walker experimented with seamer Richard Jerry as an opening batter. It didn’t work, as he was dismissed for a four-ball duck by Berg.
Berg then removed Pete Hopson before claiming the big wicket of Chris Stone. The third highest runscorer in the Premier Division this year, Stone was also out for a duck as Havant slid to 34-3.
Harry Gadd top scored with 34 before Walker called a halt to the innings at 116 when Atkins was hit for the second time off the fourth ball of the 49th over.
Berg had hit 61 off 71 balls as Lymington posted a daunting 283 after electing to bat first.
Ryan Scott reached his third SPL century - and his first since 2018 - before he was caught by Harry Gadd off his brother Freddie’s bowling for exactly 100.
After Kamran Dhariwal had struck 53, Scott and Berg added 118 for the fifth wicket.
Havant remain fourth despite their 167-run thrashing, with Lymington now just four points behind them with five weeks remaining.
Asked to sum up his side’s league season so far, Walker said: ‘It’s ok, I’m pretty content.
‘If we can end up fourth, or sneak into third, then that would be a tremendous effort from the group.
‘The youngsters have had a bit more experience, which will be crucial in a couple of years when they will be needed to take on a bigger role.’