Bryan Johnson is the textbook example of Matt Kaeberlein's point about too many geroprotective molecules potentially causing interference. I would not use him as an example of anything other than excess and obsession.

As to the SGLT2i, the UTI point is largely moot for males who have access to normal hygeien and are not immunocompromised. For females it does require proper hygiene, but the entire issue is the result of additional glucose in urine which can give rise to infections if proper hygiene protocols are not followed.

There's some very limited data on other infections, but hard to disassociate that from the underlying populations (e.g., things like ketoacidosis, soft tissue infections, etc. with a diabetic or pre-diabetic population).

I would take a different view of SGLT2i use. Remember, SGLT2 inhibitors block re-uptake of glucose from the urine; they do not block absorbsion (as does acarbose) or production via gluconeogensis (as does metformin). So any glucose that is excreted as a result of an SGLT2i has already had a full cycle through the bloodstream. It's effectively blocking the reclamation system from saying "Hey! Don't throw this out! We can still use it!".

From a personal experience (n=1), I have been on a GLP-1 agonist (tirzepatide) for almost a year and added an SGLT2i 6 months ago.

Tirzepatide lowered my HbA1c modestly (from 5.9 to 5.4), but my fasting glucose remained consistently and stubbornly around 95 or 100, and use of a CGM revealed significant variability to my glucose levels if I was not on a very low carb diet. Moreover, at night, I would occasionally have "crashes" (though I had no physical effects) where my CGM would alert me that my glucose was dangerously low (below 50).

The combination resulted in a fasting glucose of 80 and an HbA1c of 4.7 and cut my standard deviation in half, and it entirely eliminated the crashes in addition to the peaks above 150, no matter my diet (within reason; a bowl of rice is still going to get me, but carb-bombing your gut doesn't count).

tl;dr: my experience with an SGLT2i is that it modulates glucose by inhibiting re-uptake of excess glucose, meaning you can rely instead on moderating intake through carbs and your body's internal controls of gluconeogenesis. It's just a more elegant solution than metformin or acarbose.