Absolutely zero point.
As much as I like the GAU-19 this isn’t a role for it either.
Realistically you need at least a 30mm cannon simply for a practical ammunition nature for that role, and you need a radar guidance FCS.
You aren’t growing industry for those from a ragtag dual .50 mount for a Brinks Truck.
While I kind of agree with you, we are unlikely to buy much if anything. The .50 cals are in the system, as is the ammunition. There is training packages, range fans already made up. There is likley 10-20 companies that could bang the turret assemblies out pretty quickly, whether it's trailer, vehicle or palletized, it makes minimal difference. I will add anything that spends defense monies on domestic jobs stands a chance in the coming budget nightmare.
One thing that is apparent from the current conflict is that you will never have enough AD. If Canada buys an AD systems, it will be a handful, with a handful of missiles to go with it. Which means only high value targets like HQ and the tanks will get protection and your infantry will be on it's own most of the time. I take a stopgap system over a notional placeholder any day.
Supplement these with Manpads, then you are starting to see some layering, get a Geapard 2.0, another layer, get NASAMS and now we have something and the MK II version could have 20mm with better sights, which was done in WWII. For chewing up the lowend drones these will work okay.
If I was king for a year, I get a 35mm gun system with it's own radar on a K9 chassis to complement our K9 SPG's and the NASAMS as well. But I am not king, so I look for a homegrown pauper solution for a non-serious Canadian military with a non-serious government which is likley to be involved in a another world crisis totally unprepared, yet again.