How about pulling over the informants car and nail the guys for felon possession of the gun and maybe intent to commit an armed crime in order to send his butt back to prision for parole violation??
No excuse to putting an innocent person in jepordy because these 'police' won't do a felony stop.
The police in this case had adequate grounds to do a "Terry' stop and search the parolee. Could have done it outside or inside the store. All they needed was a good picture of the parolee in time to do the deed.