Help with flight? Compression socks needed?

My partner (34M) 150 lbs 5’10” has a really huge bruise on his upper thigh. he fell during skateboarding. we are flying 5-8 hours this weekend. should I encourage him to wear compression socks? I’m worried that he will get blood clots. his bruise is the on the back of his thigh and covers the majority of his back thigh.