Would be unlikely to work. the spray helps stop the bottoms riding up, not hold the buttocks in, especially against the sort of forces that that poor shirt and bra are fighting against. In all seriousness, the physics of boobs moving around during exercise is actually pretty complicated, it's part of why a good sports bra is essential. The bombshell bra isn't for dancing in, quite honestly, esp not for the girls with a fuller bust.
'tit' tape would have a better chance of holding her in, but she really needs a better fitted bra and a better shirt. However, the picture likely looks much worse than it is. it's a microsecond of time when the boob is moving one way while her body is moving another, as happens to all us boob having people, its just physics, so it looks worse than it is, as though she's busting out at all times when she isn't (if any of us were to jump up and down in our bras and someone was taking constant photos, we'd likely all have photos where it looks like we're about to spill out even when we're not as breast tissue shifts). but if i were her I'd have nipple pasties on, jic, and be taped into my bra like crazy. just to be safe.