Stupid is as stupid does: if you have a home equity line of credit AND a savings account with a non-trivial amount of money it in, you're really an idiot. An HELC in some sense IS a 'savings account' and your cash earning you 1% in a bank could/should be 'earning' you whatever your interest rate is on the HELC. $10,000 at 4% means it's costing her $400/yr to "have a savings account" ... well, not anymore.
But: what do you expect from football fans?
More seriously, if they didn't have an HELC (or savings) they'd just pay for this with a credt card. Which is better? I'd argue that it's better to put a stupid purchase on an HELC than a credit card. If you're going to use credit, you might as well do it in a way that is cheaper.
/jordan