Realistically I don't get hung up on infinity like you seem too, it is a description of a behaviour to me nothing more or less.
My issue is gravity increases to some incredible value and there are 2 obvious issues
1.) What controls the rate of drop off to whatever you want to call that bottom value ... infinity/bound?This is the issue of proportionality ... here is a plot of Earths gravity well.
Now that is a steep drop why doesn't it keep plummetting to the infinity/bound condition?
GR has an explaination for the rate of dropoff and even why the value doesn't go to infinity/bounds and so any competing theory needs to do the same.
2.) What is the nature of the interaction between matter and gravity?Ideally an alternative theory would be able to shed light on this although for its part GR does not describe what causes the interaction. GR merely places a curvature relationship in time on all space coordinates radiating out to infinity/universe bounds by some unknown process.
