It sounds too OP when you said it like that. But really, Reinforcemint + Blover combo doesn't always work for the best in the Arena.
This combo has more limitation that we might think. It only works for the best with constant plant food, otherwise, you can't spam it.
Players who can spam it are mostly those who have imitator and/or power lily, both paid plants. I don't mind p2w like spamming Reinforcemint + Blover with the help of imitator/power lily since they've paid for the plants, after all. So the way I see it is it's kinda more about the premium plants than Reinforcemint + Blover itself if you emphasize on the spamming.
Now of course there are Arena levels where plant foods are plenty, like the current tournament. But this doesn't always happen, and when it happens like now, there's more to getting plant foods from the tombs than it seems. Well, at least in jade, you'd still want to consider some strategy to destroy the tombs quickly before it respawned anew.
And when plant foods are plenty, using these plant foods for Reinforcemint + Blover combo doesn't always mean that it's the best use of the plant foods. Maybe they can be used better for a tile turnip strategy, or to refresh mints of the currently buffed family. Reinforcemint + Blover combo doesn't always give the highest score.
I do wonder how many scores did your opponent get by using Reinforcemint + Blover combo. Cause in the current tournament, even this 'mighty' combo might not give the best score compared to those strats that don't use this combo. There's more to Arena scoring than just killing zombies quickly at once. There are times when such quick kills cause the waves to arrive more slowly, thus fewer scores, or how it would be preferable to use a strat that kills the zombie general (like the current Cardio Zombie) to get higher scores, etc. The best scorer strats I observed in this forum for the last few tournaments didn't even use this combo.
I'd say it's OP when the level allows it to be (and maybe it's more about Blover than Reinforce-mint). But such level hasn't been much lately. And there's still strategy involved using this combo (like how to get constant plant foods, the timing of when to use the combo best, whether there's better use of the plant foods, etc.), so I think there's no need to patch it if it'll only lose the fun in figuring out those strats.