== Trask is the only source to mention size == 

 Trask stands alone in describing this in terms of size: 
 *P.H. Matthews, Oxford Concise Dictionary of Linguistics (2007, Oxford) uses "macrofamily" solely for a proposed unit that combines widely accepted language families with no reference to size. 
 *Lyle Campbell & Mauricio J. Mixco, A Glossary of Historical Linguistics (2007, Utah) uses "macrofamily" solely for proposed and controversial units with no reference to size. 
 *David Crystal, A Dictionary of Linguistics & Phonetics (2003, Blackwell) does not use "macrofamily", but uses "phylum" and "macrophylum" in the same senseproposed units with deep time depth above the level of established families with no reference to size. 
 *Terry Crowley, An Introduction to Historical Linguistics (1997, Oxford) does not use "macrofamily", but uses "stock" and "phylum" in the same senseproposed units with deep time depth above the level of established families with no reference to size.  Indeed, he follows Stephen A. Wurm in using "stock" for grouping language isolates as well as for grouping families. 
 So if you look at actual linguistic dictionaries, you find Trask is the only source that uses "macrofamily" for size and all the others use it only for "proposed controversial grouping above the level of family".