Diop started the season at the heart of Moyes’s defence but tested positive for coronavirus on the same night as his manager and former team-mate Josh Cullen.
In the Frenchman’s absence, Fabian Balbuena stepped into the back three, with Diop unable to displace him since.
The 23-year-old, who has been of interest to Manchester United and Tottenham since joining the Hammers, was even left out of the matchday squad for the trip to Leeds on Friday night despite travelling up to Elland Road.
With money tight amid the coronavirus pandemic, Moyes may have been tempted to move the defender on in January in order to raise funds, but insists he has no plans to do so.
“I’ve got no intention in letting any players go,” said Moyes. “Issa’s one of the players we really like.
“He started in the team, he picked up the virus at the same time as I did. Fabian Balbuena has come in and played very well, you know that’s what happens in football. But we’ve got no intention whatsoever letting Issa go. None.”
West Ham come up against London rivals Crystal Palace on Wednesday night, preparing to deal with the Eagles’ new star Eberechi Eze, who could well have been lining up in claret and blue this season.
Moyes was keen on a deal for the former QPR man over the summer, but was pipped to the signing by Roy Hodgson and Palace. The Hammers were unable to raise the funds in time, eventually landing Said Benrahma from Brentford on a loan deal which will become a £30million permanent move next year.
“I think the timing for Eze, we didn’t have the finances at the time to go for Eze when that deal was becoming available,” said Moyes.
“Things only changed for us late in the window as far as finances went really because we had other priorities, like we were trying to get a central defender in, we were looking at a full-back at the time as well. At that time we hadn’t got a great deal of money to spend.
“That changed as the window went on, [Grady] Diangana left and it just freed up a little bit of money as we went on. But at the time, we just weren’t there for Eze because we didn’t have the financial capabilities to do that.”