There is an agreement with India that SA will not arrange tests during the period the IPL tournament is held and would not force SA players employed by Indian clubs to play in tests during the said period.
The upcoming series with BanglaDesh was arranged without taking the relevant agreement in mind. The IPL starts on 26 March 2022 and if he SA Players play against the visitors, it would effectively die to Covid isolation requirements means that they will only be available as from the end of April 2022 before they can play for the IPL despite their agreement they signed with the Indian Clubs. Their livelihoods depends on the massive salaries they are paid and the cheapest players earn R1 million ranging up to R14 million for the more expensive players for the 100 week tournament.
The problem is that England force their test players to play tests in the time the IPL is on and most of them was not bid on during the recent IPL auction because of that situation.
SA Cricket gave the choice of playing for the IPL or playing for SA. It is clear that - knowing the England situation the players are unlikely to play against BanglaDesh in any event.