Well, if any participant feels unwell before the parade, the
onus is on him to fall out and not join the parade in the first
place. If he chooses to join despite being sick, then he is taking
a risk.
RSMs always warn the participants to fall out if they are not
feeling well, many times before the parade. They also make it clear
that fainting during a parade is a chargeable offence.
Let me say from personal experience, GOH will get pissed at anyone
who faints during parade b'cos the rest of us trained so blardy
hard, and one guy can spoil the whole show for us. Very little pity
for the person who fainted, b'cos we all know very well if we can't
tahan, then we shld fall out beforehand. Sounds heartless, but
that's how we felt.