Are flexible pavements not recommended in hot climates?
Answering for ICAO, no there aren't such regulations/recommendations.

All what matters to the regulatory bodies is the ACN-PCN. If seasonal changes affect the PCN, then different PCN's are to be reported.


  The bearing strength of a pavement intended for
  aircraft of apron (ramp) mass greater than 5 700 kg shall be
  made available using the aircraft classification number —
  pavement classification number (ACN-PCN) method.
  
  [...]
  
  Different PCNs may be reported if the strength of the
  pavement is subject to significant seasonal variation.
  
  — ICAO Annex 14 Chapter 2


Flexible pavements (asphalt) are actually very common in hot climates, see here: Why are most runways made of asphalt and not concrete?