From what I’ve read, sealant wouldn’t do much at the sort of pressures these guys are likely running, not sure the low pressure revolution has made it into the peloton?
It’d help but they don’t like the weight.
A normal puncture on a tubeless tyre (or tubes with sealant) you’ll lose maybe 1/3rd or 1/2 the pressure but it’s still rideable (rather than being on the rim like tubular). You almost never get a catastrophic BANG instant loss of pressure unless it’s a major gash which would have that result on any tyre system.
To be fair, they don’t really care if they write off a rim – after all unlike you and me, they’ve got plentiful supplies of kit! So the marginal gains thing of less weight always wins, even though the risk of a major loss of time is greater.