pg_walinspect float4/float8 confusion

The pg_walinspect function pg_get_wal_stats() has output arguments 
declared as float4 (count_percentage, record_size_percentage, etc.), but 
the internal computations are all done in type double.  Is there a 
reason why this is then converted to float4 for output?  It probably 
doesn't matter in practice, but it seems unnecessarily confusing.  Or at 
least add a comment so it doesn't look like an accident.  Also compare 
with pgstattuple, which uses float8 in its SQL interface for similar data.