What are the units for the bearing to center of an airport from radio aids to navigation in chart supplement?
It's almost certainly magnetic. Page 12 of the Chart Supplement (sample airport information) has this information at the bottom (emphasis mine):

All bearings and radials are magnetic unless otherwise specified. All
mileages are nautical unless otherwise noted.
All times are
Coordinated Universal Time (UTC) except as noted. All elevations are
in feet above/below Mean Sea Level (MSL) unless otherwise noted.
The
horizontal reference datum of this publication is North American Datum
of 1983 (NAD83), which for charting purposes is considered equivalent
to World Geodetic System 1984 (WGS 84).

Because this information is in a kind of footnote at the bottom of the page, I suppose you could say that it's possible it only applies to that specific page. However, the mention of &quot;this publication&quot; strongly suggests that the information applies to everything in the Chart Supplement.
You can also see that it distinguishes bearings from radials, meaning that it's highly unlikely that the word &quot;bearing&quot; is being used to mean &quot;radial&quot; on p.27.