It will be ok once you stake the legs into the ground. Off center thrust can cause one or two of the legs to lift-off the ground due to the off-axis thrust vector. Staking the legs down with tent stakes solves the problem.
Of coarse it can!
A couple years ago I converted and OLD telescope tri-pod into a MPR -HPR pad for a club buddy of mine. Below are a couple pics of the conversion.
the 3-1/2" x 1" aluminum disc have holes for Launch Rods 1/8", 3/16", 1/4", 3/8" and standard 1010 rail.
That looks like an old Orion telescope tripod...I had one with my 3? inch refractor...I remember it being fairly heavy and stable, but, that may have been with the 5? pound counterweight on it.
It is a very stable platform. If you added some weight to the tray, and/or sandbagged the legs, I would imagine you could launch G's and H's off it. One thing with the tray, it is fairly robust, but I don't remember how robust the connectors to the legs were.
In any event, I'd think you would definitely be ok with lighter weight rockets with G's, and maybe keep an eye on it as you ramp up the rocket weight and motor impulse.