Gayle will be in action, after injury, against England in Sunday's opening Twenty20 international at the Kensington Oval - where Pietersen, of course, will be absent.
The England and Wales Cricket Board axed 33-year-old Pietersen from all future plans last month, in the aftermath of their Ashes drubbing in Australia.
Windies' destructive opening batsman Gayle regrets that England's record runscorer will not be in international opposition.
He said: "I'm disappointed by the manner he (had to) bow out of international cricket. It's disrespectful.
"I don't know what happened behind closed doors...but for such a big player to actually go out like that, who has made such a big impact around the world, it's really sad.
"It's disrespectful, the way he had to go."
Pietersen must come to terms with a life in the international wilderness, albeit with riches and profile still available to him as a Twenty20 star at the Indian Premier League and elsewhere.
He spent much of Thursday evening, for example, sending wistful tweets about the possibility of phone calls coming his way - without specifiying selectors who are no longer able to pick him - after Joe Root had to leave England's Windies tour with a broken thumb.
Gayle picked up a similar theme, when he said with a smile: "I'm sure Pietersen is playing on Sunday.
"He's going to replace Joe Root.
"He's just waiting on a phone call. I hope the ECB will pick up the phone and give KP a call ... and he'll be here on Sunday playing in this game.
"If not, he'll definitely be missed. I'll be missing him personally, because he's an easy wicket for me!"
Still attempting the lighter touch, he added: "If I bowl to KP, I get him out easily, so I'm definitely going to miss him.
"I'm sure the fans are going to miss him as well, so I'll try to put on a display to entertain them."
Pietersen's fractured relationship with his employers had been in jeopardy more than once before, especially in his summer of discontent in 2012.
Gayle himself has had his own contract wrangles at times with the West Indies Cricket Board.
"It has been difficult for KP," he said.
"From my point of view, I sat out for a year - and then things worked out and we're all getting along well.
"He's been so good in international cricket I'm sure he wants to represent his country.
"He has said he wants more than 10,000 Test runs, and to cut it like this is sad for him.
"(I've just sent him) a few text messages to say it is sad to see him go out in this way."
The chance to watch England in action on television against West Indies in the tourists' one-day international series in Antigua was not enough, without Pietersen, to get Gayle out of bed early while he was recovering from his hip injury.
"Not really...I'm a late sleeper," he said. "I watched bits and pieces."
Would he have been more engaged if Pietersen was involved then?
"Maybe. I'm disappointed he's not here, and the way he went out was sad. It's frustrating for any player to go out like that."
- Sports & Recreation