Actual Infinity in Reality?

[RoadRunner79]

There was a debate ( about 18 months ago) with a Jewish Rabi (Daneil Rowe) and atheist philosopher A.C. Grayling.  One of the parts that interested me, was Rowe's point that physical things cannot be infinite or endless in extent.   This is due to the fact that physical things, are necessarily defined by their limits.  They have properties such as size, weight, position and a number of other qualities that require limits in order to define them.  He described this as being bound (finite) as opposed to being unbound.   I tried searching for this type of thought process, but didn't have much luck; finding others who described it this way.   But I thought it was interesting.

The Rabbi should perhaps stick to his religious books, instead of committing the composition fallacy.

Where do you think that the fallacy of composition is being committed here?  It seems to me that this fallacy is often casually thrown in, when such an argument is not being made.