I did misread the OP as to game vs. practice. However, that does not lead me to change my comments.
Whether the player or the parent realizes it or not, that is a big deal. And if they are told it's a big deal and their response is not to accept that, but rather, to argue with it, then that is an even bigger deal.
I'm not looking to make an enemy here, but the idea that a high school junior or senior cannot be left at home alone for even one day is one that is of fairly recent vintage, part of the ongoing trend towards helicopter parenting. Bear in mind, we're talking about a young man who's supposed to be just a little over a year from being away from home 100% of the time. If he can't handle a single day on his own, that transition is going to be one heckuva crash course.
Moreover, players have been known to be left with trusted friends' families, or with relatives. That is, the alternative is not necessarily "home alone," though again, I have no problem at all with a 17-year-old being on his own for a few days.
It's been quite a long time since I was that age, to be sure, but I was left alone many times, and no one had a second thought about it. As far as I know, the human genome has not changed that much in the intervening generation. What has changed is the insistence that high school age children be treated like pre-adolescent children in terms of the level of responsibility and trust afforded to them, even in cases where there is no history of misbehavior.
But while more and more parents are of that mindset, the high school, American Legion, and collegiate coaching community is not on board with them. So be warned, you are walking into a conflict that will not end the way you want it to, because even if you think you're right, the other side controls the outcome.
My point remains, if you are trying to demonstrate that you are ready to be a collegiate player, you shoot yourself in the foot if you plan activities that conflict with your team commitments. Whether or not you understand it, the impression you are making on those whose opinion of you will determine your outcome is strongly negative.
I think any coach would excuse an absence that was truly justified. A family funeral or wedding, for example. Beach week doesn't cut it. The family can still go, if it needs to go in June or July and not in August. It's just that the player needs to stay behind in order to honor his commitment.
I also want to be clear that I'm talking about a rising senior who is playing Legion ball and aspiring to college ball. I am not suggesting that a 12u travel ball kid be handled the same way. But I would respectfully suggest that a 17-year-old not be treated like a 12u kid.