Yes, this is true, but based on available evidence so far, it is the exception rather than the rule.
The highest viral titers (and thus relative infectivity) are when COVID19 positive patients have been symptomatic. Asymptomatic patients seem to be most likely to be able to spread it to very close, long duration contacts (i.e., family, people who live with said asymptomatic patient). Your chances of acquiring COVID19 from an asypmtomatic carrier based on a 1-2 hour exposure time in a gymnasium are going to be really, really low (unless you're right next to them and doing high risk transfer behaviors).
The spread of this virus (and all respiratory viruses) cannot be realistically stopped. Just slowed and contained. Most importantly, this is to make sure that the fairly rare folks that get really sick from it can get appropriate medical care.
Setting up a mitigation plan that limited attendees of the CIAC tourney events to a smaller number of asymptomatic people would definitely be in line with the overall goals of dealing with COVID19 from a public health perspective.
BTW, I listened to the CIAC director's interview on the radio this morning w/ Joe D. Not once did he mention that the decision was driven by direct consultation with epidemiologists/scientists/etc. It was all "superintendents", "mayors", "governors office", etc. Not that those groups haven't been briefed on the science of it by anyone. But the way he presented it makes me think there was a very strong political element to the decision (even as simple as it could help Lamont to check certain boxes to justify the "medical state of emergency" to the federal government to try and lobby for $$$, more tests, etc.--which may not be an inherently bad thing, btw).
Interesting times, to say the least.