This looks like a combination of keyword stuffing and people in the UK apparently wanting unisex products. It might be like labeling things that don't normally contain gluten as gluten-free for the extra exposure.
For example of keyword stuffing in titles consider,
- Coleman Water Repellent Instant Tourer Unisex Outdoor Pop-up Tent available in Green - 4 Persons
- Coleman Weatherproof Galiano Unisex Outdoor Pop-up Tent See Size Options Coleman Weatherproof Galiano Unisex Outdoor Pop-up Tent
- Yellowstone Waterproof Fast Pitch Unisex Outdoor Pop-Up Tent
- Regatta Waterproof Malawi Unisex Outdoor Pop-Up Tent
- Easycamp Unisex Cyrus 200 Tent, Aqua Blue, One Size
As far as the UK is concerned, I search "unisex tent" on both amazon.com and amazon.co.uk in the Sports & Outdoors section.
- amazon.com -> "Showing results for "unisex tent" in Toys & Games. Search in Sports & Outdoors instead."
- amazon.co.uk -> Lots and lots of tents.
Also supporting this theory are these results searching amazon.co.uk for "unisex"
- Kingfisher Unisex Olham Rubber Steel Shaft Camping Tent Mallet, Black
- JOOWEN Unisex Two Tone Cotton Twill Unstructured Baseball Cap Adjustable Dad Hat
- Under Armour Undeniable 3.0 Md Unisex Sport Duffel
- Gelert Unisex Wind Blocker
- NGT Unisex Stainless Baiting Tool Set in Sleeve (4 Piece), Green, One Size
- Mora Unisex 163s Spoon and Bowl Crook Carving Knife, Natural
Mallets, knives, windblockers and duffel bags don't seem to be specific to one gender, I don't see why a tent would be.