The contractor has to be there at night anyway for the main runway.
the works that are being done on 14/32 are the same as those being done on 01/19 at night, ie, VASI replacement.
They're not installing the 01/19 PAPIs yet.
They won't begin night works on the main runway PAPIs until 14/32 is finished. Basically there's only one set of guys; when they finish 14/32 they'll swing to night works for the main runway.
01/19 cannot feasibly be closed except between midnight and 5am local, but 14/32 can be closed for day works, or so the studies said. I would think that with most civil construction projects (not just aviation), night works are a last resort option due to costs and safety.
There are also other works occuring periodically on the main runway at night that are not PAPI related.