My neighbour's husband was a fireman. He did the "common" trick of taking promotions in the last few years of his service so got a whopping lump sum and good pension in his early 50s. He could have lived on it, but instead, got a high paying job at BNFL, along with a company Mercedes car! Then in his late 50's he retired from that and got another good pension.
He didn't need any more tax breaks than he already had. A tax break won't incentivise him back to work now, because his pensions are more than his wage as a lowly fireman. And he's still nowhere near state pension.
Likewise we have a family friend who's a dentist. He took early retirement and accepted a lower pension in return as the pension was still very attractive and more than enough for him to live a very comfortable lifestyle. He won't be returning to the workforce either.
Rishi needs to concentrate on looking at working conditions and why people left the workforce in the first place. If they had enough money to retire early, then gimmicks like a tax break won't get them back, and if it does, they'll just retire again when the tax break expires and they have to pay tax. How about he looks at working conditions, changing shift patterns, encouraging more flexibility - i.e. the kind of things that employers who are suffering shortages should have been doing for the last few years!
The best thing Rishi could do, if he wants to mess with the tax system to get people back in work in certain areas of shortage, is for him to accept HE made a mistake with IR35 and cancel the recent changes! It's been catastrophic for the lorry driving industry, the IT/financial services industry and the NHS!