I'll give you the benefit of the doubt and not gonna say that it is outright bad. I definitely can see the advantage, but only if you skip the weapon rack. Otherwise a vickers is almost 1.4 more expensive then a bren, while Brens have better synergy. Perhaps it is viable in 1v1, not gonna argue about that, since I don't play UKF in 1v1. Also, tightrope always tries something new and sometimes it sticks (like AssSection spam), but sometimes it does not, like countless other niche strats he tried.
But again, maybe this strat viable, but I lean towards "no" in a sweaty tryhard situation.
95% of my matches are with my premade 3v3 team, so theres plenty of open maps like Rzhev,Hill 400 etc and they still have done pretty well for the last 15 or so matches I have played with them(floating around rank 200).
Whilst you skip the 35fuel weapon rack upgrade because you don't need weapon racks teched anymore for the M3 HT to drop Vickers guns, the M3 HT in of itself still costs about 30 fuel.
But being also a mobile healing and reinforce point at that, you can also just garrison two fully upgraded IS sections inside it, meaning 4 Vickers LMG and one Lee-enfield shooting out of it, using that you can bully isolated mainline inf squads without having to worry about being snared because if he hangs around long enough to snare you, you'll be able to wipe his squad because you drove up to him to point blank range.
Or you can just drive right past setup MGs and force them to retreat easily, wouldn't recommend using this tactic past the 10 minute mark though because of the prevalence of double ATG at that stage.
Also I don't tech grenades for IS so I'll have plenty of ammo to spend on them once the M3 arrives and I usually upgrade medic package only once or twice until late game.